Experimental Realization of Continuous-Variable Quantum Error Correction Codes
DEFF Research Database (Denmark)
Lassen, Mikael Østergaard; Madsen, Lars Skovgaard; Andersen, Ulrik Lund
Quantum information processing relies on the robust and faithful transmission, storage and manipulation of quantum information. However, since different decoherent processes are inherent to any realistic implementation, the future of quantum information systems strongly relies on the ability to d...... to detect and perform error code correction and noise filtration. We present two different schemes to eliminate erasure errors and channel excess noise in continuous-variable quantum channels.......Quantum information processing relies on the robust and faithful transmission, storage and manipulation of quantum information. However, since different decoherent processes are inherent to any realistic implementation, the future of quantum information systems strongly relies on the ability...
Experimentally feasible quantum erasure-correcting code for continuous variables
DEFF Research Database (Denmark)
Nisset, J.; Andersen, Ulrik Lund; Cerf, N.J.
2008-01-01
We devise a scheme that protects quantum coherent states of light from probabilistic losses, thus achieving the first continuous-variable quantum erasure-correcting code. If the occurrence of erasures can be probed, then the decoder enables, in principle, a perfect recovery of the original light ...
Generalized concatenated quantum codes
Grassl, Markus; Shor, Peter; Smith, Graeme; Smolin, John; Zeng, Bei
2009-05-01
We discuss the concept of generalized concatenated quantum codes. This generalized concatenation method provides a systematical way for constructing good quantum codes, both stabilizer codes and nonadditive codes. Using this method, we construct families of single-error-correcting nonadditive quantum codes, in both binary and nonbinary cases, which not only outperform any stabilizer codes for finite block length but also asymptotically meet the quantum Hamming bound for large block length.
Holevo, A. S.
1998-12-01
ContentsI. IntroductionII. General considerations § 1. Quantum communication channel § 2. Entropy bound and channel capacity § 3. Formulation of the quantum coding theorem. Weak conversionIII. Proof of the direct statement of the coding theorem § 1. Channels with pure signal states § 2. Reliability function § 3. Quantum binary channel § 4. Case of arbitrary states with bounded entropyIV. c-q channels with input constraints § 1. Coding theorem § 2. Gauss channel with one degree of freedom § 3. Classical signal on quantum background noise Bibliography
Quantum Synchronizable Codes From Quadratic Residue Codes and Their Supercodes
Xie, Yixuan; Yuan, Jinhong; Fujiwara, Yuichiro
2014-01-01
Quantum synchronizable codes are quantum error-correcting codes designed to correct the effects of both quantum noise and block synchronization errors. While it is known that quantum synchronizable codes can be constructed from cyclic codes that satisfy special properties, only a few classes of cyclic codes have been proved to give promising quantum synchronizable codes. In this paper, using quadratic residue codes and their supercodes, we give a simple construction for quantum synchronizable...
Asymmetric Quantum Codes on Toric Surfaces
DEFF Research Database (Denmark)
Hansen, Johan P.
2017-01-01
Asymmetric quantum error-correcting codes are quantum codes defined over biased quantum channels: qubit-flip and phase-shift errors may have equal or different probabilities. The code construction is the Calderbank-Shor-Steane construction based on two linear codes. We present families of toric...... surfaces, toric codes and associated asymmetric quantum error-correcting codes....
Continuous-variable quantum erasure correcting code
DEFF Research Database (Denmark)
Lassen, Mikael Østergaard; Sabuncu, Metin; Huck, Alexander
2010-01-01
We experimentally demonstrate a continuous variable quantum erasure-correcting code, which protects coherent states of light against complete erasure. The scheme encodes two coherent states into a bi-party entangled state, and the resulting 4-mode code is conveyed through 4 independent channels...
Quantum coding with finite resources
Tomamichel, Marco; Berta, Mario; Renes, Joseph M.
2016-01-01
The quantum capacity of a memoryless channel determines the maximal rate at which we can communicate reliably over asymptotically many uses of the channel. Here we illustrate that this asymptotic characterization is insufficient in practical scenarios where decoherence severely limits our ability to manipulate large quantum systems in the encoder and decoder. In practical settings, we should instead focus on the optimal trade-off between three parameters: the rate of the code, the size of the quantum devices at the encoder and decoder, and the fidelity of the transmission. We find approximate and exact characterizations of this trade-off for various channels of interest, including dephasing, depolarizing and erasure channels. In each case, the trade-off is parameterized by the capacity and a second channel parameter, the quantum channel dispersion. In the process, we develop several bounds that are valid for general quantum channels and can be computed for small instances. PMID:27156995
Quantum Quasi-Cyclic LDPC Codes
Hagiwara, Manabu; Imai, Hideki
2007-01-01
In this paper, a construction of a pair of "regular" quasi-cyclic LDPC codes as ingredient codes for a quantum error-correcting code is proposed. That is, we find quantum regular LDPC codes with various weight distributions. Furthermore our proposed codes have lots of variations for length, code rate. These codes are obtained by a descrete mathematical characterization for model matrices of quasi-cyclic LDPC codes. Our proposed codes achieve a bounded distance decoding (BDD) bound, or known a...
Entanglement-assisted quantum MDS codes constructed from negacyclic codes
Chen, Jianzhang; Huang, Yuanyuan; Feng, Chunhui; Chen, Riqing
2017-12-01
Recently, entanglement-assisted quantum codes have been constructed from cyclic codes by some scholars. However, how to determine the number of shared pairs required to construct entanglement-assisted quantum codes is not an easy work. In this paper, we propose a decomposition of the defining set of negacyclic codes. Based on this method, four families of entanglement-assisted quantum codes constructed in this paper satisfy the entanglement-assisted quantum Singleton bound, where the minimum distance satisfies q+1 ≤ d≤ n+2/2. Furthermore, we construct two families of entanglement-assisted quantum codes with maximal entanglement.
Degenerate quantum codes and the quantum Hamming bound
Sarvepalli, Pradeep; Klappenecker, Andreas
2010-03-01
The parameters of a nondegenerate quantum code must obey the Hamming bound. An important open problem in quantum coding theory is whether the parameters of a degenerate quantum code can violate this bound for nondegenerate quantum codes. In this article we show that Calderbank-Shor-Steane (CSS) codes, over a prime power alphabet q⩾5, cannot beat the quantum Hamming bound. We prove a quantum version of the Griesmer bound for the CSS codes, which allows us to strengthen the Rains’ bound that an [[n,k,d
Construction of new quantum MDS codes derived from constacyclic codes
Taneja, Divya; Gupta, Manish; Narula, Rajesh; Bhullar, Jaskaran
Obtaining quantum maximum distance separable (MDS) codes from dual containing classical constacyclic codes using Hermitian construction have paved a path to undertake the challenges related to such constructions. Using the same technique, some new parameters of quantum MDS codes have been constructed here. One set of parameters obtained in this paper has achieved much larger distance than work done earlier. The remaining constructed parameters of quantum MDS codes have large minimum distance and were not explored yet.
Relating quantum discord with the quantum dense coding capacity
Energy Technology Data Exchange (ETDEWEB)
Wang, Xin; Qiu, Liang, E-mail: lqiu@cumt.edu.cn; Li, Song; Zhang, Chi [China University of Mining and Technology, School of Sciences (China); Ye, Bin [China University of Mining and Technology, School of Information and Electrical Engineering (China)
2015-01-15
We establish the relations between quantum discord and the quantum dense coding capacity in (n + 1)-particle quantum states. A necessary condition for the vanishing discord monogamy score is given. We also find that the loss of quantum dense coding capacity due to decoherence is bounded below by the sum of quantum discord. When these results are restricted to three-particle quantum states, some complementarity relations are obtained.
Upper bound on quantum stabilizer codes
Li, Zhuo; Xing, Li-Juan
2009-03-01
By studying sets of operators having constant weight, we present an analytical upper bound on the pure quantum stabilizer codes whose underlying quantum system can be of arbitrary dimension, which outperforms the well-known quantum Hamming bound, the optimal analytical upper bound so far for small code length.
Experimental quantum forgery of quantum optical money
Bartkiewicz, Karol; Černoch, Antonín; Chimczak, Grzegorz; Lemr, Karel; Miranowicz, Adam; Nori, Franco
2017-03-01
Unknown quantum information cannot be perfectly copied (cloned). This statement is the bedrock of quantum technologies and quantum cryptography, including the seminal scheme of Wiesner's quantum money, which was the first quantum-cryptographic proposal. Surprisingly, to our knowledge, quantum money has not been tested experimentally yet. Here, we experimentally revisit the Wiesner idea, assuming a banknote to be an image encoded in the polarization states of single photons. We demonstrate that it is possible to use quantum states to prepare a banknote that cannot be ideally copied without making the owner aware of only unauthorized actions. We provide the security conditions for quantum money by investigating the physically-achievable limits on the fidelity of 1-to-2 copying of arbitrary sequences of qubits. These results can be applied as a security measure in quantum digital right management.
Experimental quantum data locking
Liu, Yang; Cao, Zhu; Wu, Cheng; Fukuda, Daiji; You, Lixing; Zhong, Jiaqiang; Numata, Takayuki; Chen, Sijing; Zhang, Weijun; Shi, Sheng-Cai; Lu, Chao-Yang; Wang, Zhen; Ma, Xiongfeng; Fan, Jingyun; Zhang, Qiang; Pan, Jian-Wei
2016-08-01
Classical correlation can be locked via quantum means: quantum data locking. With a short secret key, one can lock an exponentially large amount of information in order to make it inaccessible to unauthorized users without the key. Quantum data locking presents a resource-efficient alternative to one-time pad encryption which requires a key no shorter than the message. We report experimental demonstrations of a quantum data locking scheme originally proposed by D. P. DiVincenzo et al. [Phys. Rev. Lett. 92, 067902 (2004), 10.1103/PhysRevLett.92.067902] and a loss-tolerant scheme developed by O. Fawzi et al. [J. ACM 60, 44 (2013), 10.1145/2518131]. We observe that the unlocked amount of information is larger than the key size in both experiments, exhibiting strong violation of the incremental proportionality property of classical information theory. As an application example, we show the successful transmission of a photo over a lossy channel with quantum data (un)locking and error correction.
Methodology for bus layout for topological quantum error correcting codes
Energy Technology Data Exchange (ETDEWEB)
Wosnitzka, Martin; Pedrocchi, Fabio L.; DiVincenzo, David P. [RWTH Aachen University, JARA Institute for Quantum Information, Aachen (Germany)
2016-12-15
Most quantum computing architectures can be realized as two-dimensional lattices of qubits that interact with each other. We take transmon qubits and transmission line resonators as promising candidates for qubits and couplers; we use them as basic building elements of a quantum code. We then propose a simple framework to determine the optimal experimental layout to realize quantum codes. We show that this engineering optimization problem can be reduced to the solution of standard binary linear programs. While solving such programs is a NP-hard problem, we propose a way to find scalable optimal architectures that require solving the linear program for a restricted number of qubits and couplers. We apply our methods to two celebrated quantum codes, namely the surface code and the Fibonacci code. (orig.)
Quantum internet using code division multiple access
Zhang, Jing; Liu, Yu-xi; Özdemir, Şahin Kaya; Wu, Re-Bing; Gao, Feifei; Wang, Xiang-Bin; Yang, Lan; Nori, Franco
2013-01-01
A crucial open problem inS large-scale quantum networks is how to efficiently transmit quantum data among many pairs of users via a common data-transmission medium. We propose a solution by developing a quantum code division multiple access (q-CDMA) approach in which quantum information is chaotically encoded to spread its spectral content, and then decoded via chaos synchronization to separate different sender-receiver pairs. In comparison to other existing approaches, such as frequency division multiple access (FDMA), the proposed q-CDMA can greatly increase the information rates per channel used, especially for very noisy quantum channels. PMID:23860488
The Mathematics of Error Correcting Quantum Codes
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 6; Issue 3. The Mathematics of Error Correcting-Quantum Codes - Quantum Probability. K R Parthasarathy. General Article Volume 6 Issue 3 March 2001 pp 34-45. Fulltext. Click here to view fulltext PDF. Permanent link:
Some Families of Asymmetric Quantum MDS Codes Constructed from Constacyclic Codes
Huang, Yuanyuan; Chen, Jianzhang; Feng, Chunhui; Chen, Riqing
2017-10-01
Quantum maximal-distance-separable (MDS) codes that satisfy quantum Singleton bound with different lengths have been constructed by some researchers. In this paper, seven families of asymmetric quantum MDS codes are constructed by using constacyclic codes. We weaken the case of Hermitian-dual containing codes that can be applied to construct asymmetric quantum MDS codes with parameters [[n,k,dz/dx
Experimental search for quantum gravity
2018-01-01
This book summarizes recent developments in the research area of quantum gravity phenomenology. A series of short and nontechnical essays lays out the prospects of various experimental possibilities and their current status. Finding observational evidence for the quantization of space-time was long thought impossible. In the last decade however, new experimental design and technological advances have changed the research landscape and opened new perspectives on quantum gravity. Formerly dominated by purely theoretical constructions, quantum gravity now has a lively phenomenology to offer. From high precision measurements using macroscopic quantum oscillators to new analysis methods of the cosmic microwave background, no stone is being left unturned in the experimental search for quantum gravity. This book sheds new light on the connection of astroparticle physics with the quantum gravity problem. Gravitational waves and their detection are covered. It illustrates findings from the interconnection between gene...
Experimental Aspects of Quantum Computing
Everitt, Henry O
2005-01-01
Practical quantum computing still seems more than a decade away, and researchers have not even identified what the best physical implementation of a quantum bit will be. There is a real need in the scientific literature for a dialog on the topic of lessons learned and looming roadblocks. These papers, which appeared in the journal of "Quantum Information Processing" are dedicated to the experimental aspects of quantum computing These papers highlight the lessons learned over the last ten years, outline the challenges over the next ten years, and discuss the most promising physical implementations of quantum computing.
Classical codes in quantum state space
Howard, Mark
2015-12-01
We present a construction of Hermitian operators and quantum states labelled by strings from a finite field. The distance between these operators or states is then simply related (typically, proportional) to the Hamming distance between their corresponding strings. This allows a straightforward application of classical coding theory to find arrangements of operators or states with a given distance distribution. Using the simplex or extended Reed-Solomon code in our construction recovers the discrete Wigner function, which has important applications in quantum information theory.
Concatenated codes for fault tolerant quantum computing
Energy Technology Data Exchange (ETDEWEB)
Knill, E.; Laflamme, R.; Zurek, W.
1995-05-01
The application of concatenated codes to fault tolerant quantum computing is discussed. We have previously shown that for quantum memories and quantum communication, a state can be transmitted with error {epsilon} provided each gate has error at most c{epsilon}. We show how this can be used with Shor`s fault tolerant operations to reduce the accuracy requirements when maintaining states not currently participating in the computation. Viewing Shor`s fault tolerant operations as a method for reducing the error of operations, we give a concatenated implementation which promises to propagate the reduction hierarchically. This has the potential of reducing the accuracy requirements in long computations.
A surface code quantum computer in silicon
Hill, Charles D.; Peretz, Eldad; Hile, Samuel J.; House, Matthew G.; Fuechsle, Martin; Rogge, Sven; Simmons, Michelle Y.; Hollenberg, Lloyd C. L.
2015-01-01
The exceptionally long quantum coherence times of phosphorus donor nuclear spin qubits in silicon, coupled with the proven scalability of silicon-based nano-electronics, make them attractive candidates for large-scale quantum computing. However, the high threshold of topological quantum error correction can only be captured in a two-dimensional array of qubits operating synchronously and in parallel—posing formidable fabrication and control challenges. We present an architecture that addresses these problems through a novel shared-control paradigm that is particularly suited to the natural uniformity of the phosphorus donor nuclear spin qubit states and electronic confinement. The architecture comprises a two-dimensional lattice of donor qubits sandwiched between two vertically separated control layers forming a mutually perpendicular crisscross gate array. Shared-control lines facilitate loading/unloading of single electrons to specific donors, thereby activating multiple qubits in parallel across the array on which the required operations for surface code quantum error correction are carried out by global spin control. The complexities of independent qubit control, wave function engineering, and ad hoc quantum interconnects are explicitly avoided. With many of the basic elements of fabrication and control based on demonstrated techniques and with simulated quantum operation below the surface code error threshold, the architecture represents a new pathway for large-scale quantum information processing in silicon and potentially in other qubit systems where uniformity can be exploited. PMID:26601310
A surface code quantum computer in silicon.
Hill, Charles D; Peretz, Eldad; Hile, Samuel J; House, Matthew G; Fuechsle, Martin; Rogge, Sven; Simmons, Michelle Y; Hollenberg, Lloyd C L
2015-10-01
The exceptionally long quantum coherence times of phosphorus donor nuclear spin qubits in silicon, coupled with the proven scalability of silicon-based nano-electronics, make them attractive candidates for large-scale quantum computing. However, the high threshold of topological quantum error correction can only be captured in a two-dimensional array of qubits operating synchronously and in parallel-posing formidable fabrication and control challenges. We present an architecture that addresses these problems through a novel shared-control paradigm that is particularly suited to the natural uniformity of the phosphorus donor nuclear spin qubit states and electronic confinement. The architecture comprises a two-dimensional lattice of donor qubits sandwiched between two vertically separated control layers forming a mutually perpendicular crisscross gate array. Shared-control lines facilitate loading/unloading of single electrons to specific donors, thereby activating multiple qubits in parallel across the array on which the required operations for surface code quantum error correction are carried out by global spin control. The complexities of independent qubit control, wave function engineering, and ad hoc quantum interconnects are explicitly avoided. With many of the basic elements of fabrication and control based on demonstrated techniques and with simulated quantum operation below the surface code error threshold, the architecture represents a new pathway for large-scale quantum information processing in silicon and potentially in other qubit systems where uniformity can be exploited.
Experimental quantum computing without entanglement.
Lanyon, B P; Barbieri, M; Almeida, M P; White, A G
2008-11-14
Deterministic quantum computation with one pure qubit (DQC1) is an efficient model of computation that uses highly mixed states. Unlike pure-state models, its power is not derived from the generation of a large amount of entanglement. Instead it has been proposed that other nonclassical correlations are responsible for the computational speedup, and that these can be captured by the quantum discord. In this Letter we implement DQC1 in an all-optical architecture, and experimentally observe the generated correlations. We find no entanglement, but large amounts of quantum discord-except in three cases where an efficient classical simulation is always possible. Our results show that even fully separable, highly mixed, states can contain intrinsically quantum mechanical correlations and that these could offer a valuable resource for quantum information technologies.
A Construction of MDS Quantum Convolutional Codes
Zhang, Guanghui; Chen, Bocong; Li, Liangchen
2015-09-01
In this paper, two new families of MDS quantum convolutional codes are constructed. The first one can be regarded as a generalization of [36, Theorem 6.5], in the sense that we do not assume that q≡1 (mod 4). More specifically, we obtain two classes of MDS quantum convolutional codes with parameters: (i) [( q 2+1, q 2-4 i+3,1;2,2 i+2)] q , where q≥5 is an odd prime power and 2≤ i≤( q-1)/2; (ii) , where q is an odd prime power with the form q=10 m+3 or 10 m+7 ( m≥2), and 2≤ i≤2 m-1.
Self-orthogonal codes with dual distance three and quantum codes with distance three over
Liang, Fangchi
2013-12-01
Self-orthogonal codes with dual distance three and quantum codes with distance three constructed from self-orthogonal codes over are discussed in this paper. Firstly, for given code length , a self-orthogonal code with minimal dimension and dual distance three is constructed. Secondly, for each , two nested self-orthogonal codes with dual distance two and three are constructed, and consequently quantum code of length and distance three is constructed via Steane construction. All of these quantum codes constructed via Steane construction are optimal or near optimal according to the quantum Hamming bound.
A construction of quantum turbo product codes based on CSS-type quantum convolutional codes
Xiao, Hailin; Ni, Ju; Xie, Wu; Ouyang, Shan
As in classical coding theory, turbo product codes (TPCs) through serially concatenated block codes can achieve approximatively Shannon capacity limit and have low decoding complexity. However, special requirements in the quantum setting severely limit the structures of turbo product codes (QTPCs). To design a good structure for QTPCs, we present a new construction of QTPCs with the interleaved serial concatenation of CSS(L1,L2)-type quantum convolutional codes (QCCs). First, CSS(L1,L2)-type QCCs are proposed by exploiting the theory of CSS-type quantum stabilizer codes and QCCs, and the description and the analysis of encoder circuit are greatly simplified in the form of Hadamard gates and C-NOT gates. Second, the interleaved coded matrix of QTPCs is derived by quantum permutation SWAP gate definition. Finally, we prove the corresponding relation on the minimum Hamming distance of QTPCs associated with classical TPCs, and describe the state diagram of encoder and decoder of QTPCs that have a highly regular structure and simple design idea.
Repetition versus noiseless quantum codes for correlated errors
Energy Technology Data Exchange (ETDEWEB)
Cafaro, Carlo, E-mail: carlo.cafaro@unicam.i [Dipartimento di Fisica, Universita di Camerino, I-62032 Camerino (Italy); Mancini, Stefano, E-mail: stefano.mancini@unicam.i [Dipartimento di Fisica, Universita di Camerino, I-62032 Camerino (Italy)
2010-06-07
We study the performance of simple quantum error correcting codes with respect to correlated noise errors characterized by a finite correlation strength {mu}. Specifically, we consider bit flip (phase flip) noisy quantum memory channels and use repetition and noiseless quantum codes. We characterize the performance of the codes by means of the entanglement fidelity F({mu},p) as function of the error probability p and degree of memory {mu}. Finally, comparing the entanglement fidelities of repetition and noiseless quantum codes, we find a threshold {mu}{sup *}(p) for the correlation strength that allows to select the code with better performance.
Energy Technology Data Exchange (ETDEWEB)
Xiao, Hailin [Wenzhou University, College of Physics and Electronic Information Engineering, Wenzhou (China); Southeast University, National Mobile Communications Research Laboratory, Nanjing (China); Guilin University of Electronic Technology, Ministry of Education, Key Laboratory of Cognitive Radio and Information Processing, Guilin (China); Zhang, Zhongshan [University of Science and Technology Beijing, Beijing Engineering and Technology Research Center for Convergence Networks and Ubiquitous Services, Beijing (China); Chronopoulos, Anthony Theodore [University of Texas at San Antonio, Department of Computer Science, San Antonio, TX (United States)
2017-10-15
In quantum computing, nice error bases as generalization of the Pauli basis were introduced by Knill. These bases are known to be projective representations of finite groups. In this paper, we propose a group representation approach to the study of quantum stabilizer codes. We utilize this approach to define decoherence-free subspaces (DFSs). Unlike previous studies of DFSs, this type of DFSs does not involve any spatial symmetry assumptions on the system-environment interaction. Thus, it can be used to construct quantum error-avoiding codes (QEACs) that are fault tolerant automatically. We also propose a new simple construction of QEACs and subsequently develop several classes of QEACs. Finally, we present numerical simulation results encoding the logical error rate over physical error rate on the fidelity performance of these QEACs. Our study demonstrates that DFSs-based QEACs are capable of providing a generalized and unified framework for error-avoiding methods. (orig.)
Xiao, Hailin; Zhang, Zhongshan; Chronopoulos, Anthony Theodore
2017-10-01
In quantum computing, nice error bases as generalization of the Pauli basis were introduced by Knill. These bases are known to be projective representations of finite groups. In this paper, we propose a group representation approach to the study of quantum stabilizer codes. We utilize this approach to define decoherence-free subspaces (DFSs). Unlike previous studies of DFSs, this type of DFSs does not involve any spatial symmetry assumptions on the system-environment interaction. Thus, it can be used to construct quantum error-avoiding codes (QEACs) that are fault tolerant automatically. We also propose a new simple construction of QEACs and subsequently develop several classes of QEACs. Finally, we present numerical simulation results encoding the logical error rate over physical error rate on the fidelity performance of these QEACs. Our study demonstrates that DFSs-based QEACs are capable of providing a generalized and unified framework for error-avoiding methods.
Experimental quantum secret sharing and third-man quantum cryptography.
Chen, Yu-Ao; Zhang, An-Ning; Zhao, Zhi; Zhou, Xiao-Qi; Lu, Chao-Yang; Peng, Cheng-Zhi; Yang, Tao; Pan, Jian-Wei
2005-11-11
Quantum secret sharing (QSS) and third-man quantum cryptography (TQC) are essential for advanced quantum communication; however, the low intensity and fragility of the multiphoton entanglement source in previous experiments have made their realization an extreme experimental challenge. Here, we develop and exploit an ultrastable high intensity source of four-photon entanglement to report an experimental realization of QSS and TQC. The technology developed in our experiment will be important for future multiparty quantum communication.
Report on HOM experimental methods and code
Shinton, I R R; Flisgen, T
2013-01-01
Experimental methods and various codes used are reported on with the aim to understand the signals picked up from the higher order modes in the third harmonic cavities within the ACC39 module at FLASH. Both commercial computer codes have been used, and also codes written for the express purpose of understanding the sensitivity of the modal profiles to geometrical errors and other sources of experimental errors.
Maximal entanglement entanglement-assisted quantum codes of distance three
Guo, Luobin; Fu, Qiang; Li, Ruihu; Lu, Liangdong
2015-02-01
Entanglement-assisted quantum error correcting code (EAQECC) is a generalization of standard stabilizer quantum code. Maximal entanglement EAQECCs can achieve the EA-hashing bound asymptotically. In this work, we give elementary recursive constructions of quaternary zero radical codes with dual distance three for all n ≥ 4. Consequently, good maximal entanglement EAQECCs of minimum distance three for such length n are obtained. Almost all of these EAQECCs are optimal or near optimal according to the EA-quantum Hamming bound.
Experimental realization of nonadiabatic holonomic quantum computation.
Feng, Guanru; Xu, Guofu; Long, Guilu
2013-05-10
Because of its geometric nature, holonomic quantum computation is fault tolerant against certain types of control errors. Although proposed more than a decade ago, the experimental realization of holonomic quantum computation is still an open challenge. In this Letter, we report the first experimental demonstration of nonadiabatic holonomic quantum computation in a liquid NMR quantum information processor. Two noncommuting one-qubit holonomic gates, rotations about x and z axes, and the two-qubit holonomic CNOT gate are realized by evolving the work qubits and an ancillary qubit nonadiabatically. The successful realizations of these universal elementary gates in nonadiabatic holonomic quantum computation demonstrates the experimental feasibility of this quantum computing paradigm.
Improved classical and quantum random access codes
Liabøtrø, O.
2017-05-01
A (quantum) random access code ((Q)RAC) is a scheme that encodes n bits into m (qu)bits such that any of the n bits can be recovered with a worst case probability p >1/2 . We generalize (Q)RACs to a scheme encoding n d -levels into m (quantum) d -levels such that any d -level can be recovered with the probability for every wrong outcome value being less than 1/d . We construct explicit solutions for all n ≤d/2m-1 d -1 . For d =2 , the constructions coincide with those previously known. We show that the (Q)RACs are d -parity oblivious, generalizing ordinary parity obliviousness. We further investigate optimization of the success probabilities. For d =2 , we use the measure operators of the previously best-known solutions, but improve the encoding states to give a higher success probability. We conjecture that for maximal (n =4m-1 ,m ,p ) QRACs, p =1/2 {1 +[(√{3}+1)m-1 ] -1} is possible, and show that it is an upper bound for the measure operators that we use. We then compare (n ,m ,pq) QRACs with classical (n ,2 m ,pc) RACs. We can always find pq≥pc , but the classical code gives information about every input bit simultaneously, while the QRAC only gives information about a subset. For several different (n ,2 ,p ) QRACs, we see the same trade-off, as the best p values are obtained when the number of bits that can be obtained simultaneously is as small as possible. The trade-off is connected to parity obliviousness, since high certainty information about several bits can be used to calculate probabilities for parities of subsets.
Superdense coding facilitated by hyper-entanglement and quantum networks
Smith, James F.
2017-05-01
A method of generating superdense coding based on quantum hyper-entanglement and facilitated by quantum networks is discussed. Superdense coding refers to the coding of more than one classical bit into each qubit. Quantum hyperentanglement refers to quantum entanglement in more than one degree of freedom, e.g. polarization, energy-time, and orbital angular momentum (OAM). The new superdense coding scheme permits 2L bits to be encoded into each qubit where L is the number of degrees of freedom used for quantum hyper-entanglement. The superdense coding procedure is based on a generalization of the Bell state for L degrees of freedom. Theory describing the structure, generation/transmission, and detection of the generalized Bell state is developed. Circuit models are provided describing the generation/transmission process and detection process. Detection processes are represented mathematically as projection operators. A mathematical proof that that the detection scheme permits the generalized Bell states to be distinguished with 100% probability is provided. Measures of effectiveness (MOEs) are derived for the superdense coding scheme based on open systems theory represented in terms of density operators. Noise and loss related to generation/transmission, detection and propagation are included. The MOEs include various probabilities, quantum Chernoff bound, a measure of the number of message photons that must be transmitted to successfully send and receive a message, SNR and the quantum Cramer Rao' lower bound. Quantum networks with quantum memory are used to increase the efficiency of the superdense coding scheme.
A novel quantum LSB-based steganography method using the Gray code for colored quantum images
Heidari, Shahrokh; Farzadnia, Ehsan
2017-10-01
As one of the prevalent data-hiding techniques, steganography is defined as the act of concealing secret information in a cover multimedia encompassing text, image, video and audio, imperceptibly, in order to perform interaction between the sender and the receiver in which nobody except the receiver can figure out the secret data. In this approach a quantum LSB-based steganography method utilizing the Gray code for quantum RGB images is investigated. This method uses the Gray code to accommodate two secret qubits in 3 LSBs of each pixel simultaneously according to reference tables. Experimental consequences which are analyzed in MATLAB environment, exhibit that the present schema shows good performance and also it is more secure and applicable than the previous one currently found in the literature.
Decoy state method for quantum cryptography based on phase coding into faint laser pulses
Kulik, S. P.; Molotkov, S. N.
2017-12-01
We discuss the photon number splitting attack (PNS) in systems of quantum cryptography with phase coding. It is shown that this attack, as well as the structural equations for the PNS attack for phase encoding, differs physically from the analogous attack applied to the polarization coding. As far as we know, in practice, in all works to date processing of experimental data has been done for phase coding, but using formulas for polarization coding. This can lead to inadequate results for the length of the secret key. These calculations are important for the correct interpretation of the results, especially if it concerns the criterion of secrecy in quantum cryptography.
Quantum algorithms and the genetic code
Indian Academy of Sciences (India)
Home; Journals; Pramana – Journal of Physics; Volume 56; Issue 2-3. Quantum ... Quantum information processing Volume 56 Issue 2-3 February-March 2001 pp 367-381 ... Quantum mechanics; computation; database search; genetic information; DNA; nucleotide base; protein; amino acid; enzyme; quantum coherence.
Efficient Quantum Private Communication Based on Dynamic Control Code Sequence
Cao, Zheng-Wen; Feng, Xiao-Yi; Peng, Jin-Ye; Zeng, Gui-Hua; Qi, Jin
2017-04-01
Based on chaos and quantum properties, we propose a quantum private communication scheme with dynamic control code sequence. The initial sequence is obtained via chaotic systems, and the control code sequence is derived by grouping, XOR and extracting. A shift cycle algorithm is designed to enable the dynamic change of control code sequence. Analysis shows that transmission efficiency could reach 100 % with high dynamics and security.
Experimental quantum fingerprinting with weak coherent pulses
Xu, Feihu; Arrazola, Juan Miguel; Wei, Kejin; Wang, Wenyuan; Palacios-Avila, Pablo; Feng, Chen; Sajeed, Shihan; Lütkenhaus, Norbert; Lo, Hoi-Kwong
2015-01-01
Quantum communication holds the promise of creating disruptive technologies that will play an essential role in future communication networks. For example, the study of quantum communication complexity has shown that quantum communication allows exponential reductions in the information that must be transmitted to solve distributed computational tasks. Recently, protocols that realize this advantage using optical implementations have been proposed. Here we report a proof-of-concept experimental demonstration of a quantum fingerprinting system that is capable of transmitting less information than the best-known classical protocol. Our implementation is based on a modified version of a commercial quantum key distribution system using off-the-shelf optical components over telecom wavelengths, and is practical for messages as large as 100 Mbits, even in the presence of experimental imperfections. Our results provide a first step in the development of experimental quantum communication complexity. PMID:26515586
Experimental quantum compressed sensing for a seven-qubit system
Riofrío, C. A.; Gross, D.; Flammia, S. T.; Monz, T.; Nigg, D.; Blatt, R.; Eisert, J.
2017-05-01
Well-controlled quantum devices with their increasing system size face a new roadblock hindering further development of quantum technologies. The effort of quantum tomography--the reconstruction of states and processes of a quantum device--scales unfavourably: state-of-the-art systems can no longer be characterized. Quantum compressed sensing mitigates this problem by reconstructing states from incomplete data. Here we present an experimental implementation of compressed tomography of a seven-qubit system--a topological colour code prepared in a trapped ion architecture. We are in the highly incomplete--127 Pauli basis measurement settings--and highly noisy--100 repetitions each--regime. Originally, compressed sensing was advocated for states with few non-zero eigenvalues. We argue that low-rank estimates are appropriate in general since statistical noise enables reliable reconstruction of only the leading eigenvectors. The remaining eigenvectors behave consistently with a random-matrix model that carries no information about the true state.
Quantum probabilities from quantum entanglement: experimentally unpacking the Born rule
Harris, Jérémie; Bouchard, Frédéric; Santamato, Enrico; Zurek, Wojciech H.; Boyd, Robert W.; Karimi, Ebrahim
2016-05-01
The Born rule, a foundational axiom used to deduce probabilities of events from wavefunctions, is indispensable in the everyday practice of quantum physics. It is also key in the quest to reconcile the ostensibly inconsistent laws of the quantum and classical realms, as it confers physical significance to reduced density matrices, the essential tools of decoherence theory. Following Bohr’s Copenhagen interpretation, textbooks postulate the Born rule outright. However, recent attempts to derive it from other quantum principles have been successful, holding promise for simplifying and clarifying the quantum foundational bedrock. A major family of derivations is based on envariance, a recently discovered symmetry of entangled quantum states. Here, we identify and experimentally test three premises central to these envariance-based derivations, thus demonstrating, in the microworld, the symmetries from which the Born rule is derived. Further, we demonstrate envariance in a purely local quantum system, showing its independence from relativistic causality.
Experimental plug and play quantum coin flipping
Pappa, Anna; Jouguet, Paul; Lawson, Thomas; Chailloux, André; Legré, Matthieu; Trinkler, Patrick; Kerenidis, Iordanis; Diamanti, Eleni
2014-04-01
Performing complex cryptographic tasks will be an essential element in future quantum communication networks. These tasks are based on a handful of fundamental primitives, such as coin flipping, where two distrustful parties wish to agree on a randomly generated bit. Although it is known that quantum versions of these primitives can offer information-theoretic security advantages with respect to classical protocols, a demonstration of such an advantage in a practical communication scenario has remained elusive. Here we experimentally implement a quantum coin flipping protocol that performs strictly better than classically possible over a distance suitable for communication over metropolitan area optical networks. The implementation is based on a practical plug and play system, developed by significantly enhancing a commercial quantum key distribution device. Moreover, we provide combined quantum coin flipping protocols that are almost perfectly secure against bounded adversaries. Our results offer a useful toolbox for future secure quantum communications.
Towards Holography via Quantum Source-Channel Codes.
Pastawski, Fernando; Eisert, Jens; Wilming, Henrik
2017-07-14
While originally motivated by quantum computation, quantum error correction (QEC) is currently providing valuable insights into many-body quantum physics, such as topological phases of matter. Furthermore, mounting evidence originating from holography research (AdS/CFT) indicates that QEC should also be pertinent for conformal field theories. With this motivation in mind, we introduce quantum source-channel codes, which combine features of lossy compression and approximate quantum error correction, both of which are predicted in holography. Through a recent construction for approximate recovery maps, we derive guarantees on its erasure decoding performance from calculations of an entropic quantity called conditional mutual information. As an example, we consider Gibbs states of the transverse field Ising model at criticality and provide evidence that they exhibit nontrivial protection from local erasure. This gives rise to the first concrete interpretation of a bona fide conformal field theory as a quantum error correcting code. We argue that quantum source-channel codes are of independent interest beyond holography.
Entanglement-enhanced quantum error-correcting codes
Dong, Ying; Deng, Xiuhao; Jiang, Mingming; Chen, Qing; Yu, Sixia
2009-04-01
Via explicit examples we show that the pre-existing entanglement can really enhance (not only behave as an assistance for) the efficiency of the quantum error-correcting codes (QECCs) in a single block of encoding or decoding as well as help in beating the quantum Hamming bound. A systematic approach to constructing entanglement-assisted (or enhanced) quantum error-correcting codes (EAQECCs) via graph states is also presented, and an infinite family of entanglement-enhanced codes has been constructed. Furthermore we generalize the EAQECCs to the case of not-so-perfectly protected qubit and introduce the quantity infidelity as a figure of merit and show that the EAQECCs also outperform the ordinary QECCs.
Experimental loss-tolerant quantum coin flipping
Berlín, Guido; Brassard, Gilles; Bussières, Félix; Godbout, Nicolas; Slater, Joshua A.; Tittel, Wolfgang
2011-11-01
Coin flipping is a cryptographic primitive in which two distrustful parties wish to generate a random bit to choose between two alternatives. This task is impossible to realize when it relies solely on the asynchronous exchange of classical bits: one dishonest player has complete control over the final outcome. It is only when coin flipping is supplemented with quantum communication that this problem can be alleviated, although partial bias remains. Unfortunately, practical systems are subject to loss of quantum data, which allows a cheater to force a bias that is complete or arbitrarily close to complete in all previous protocols and implementations. Here we report on the first experimental demonstration of a quantum coin-flipping protocol for which loss cannot be exploited to cheat better. By eliminating the problem of loss, which is unavoidable in any realistic setting, quantum coin flipping takes a significant step towards real-world applications of quantum communication.
Quantum gravity from theory to experimental search
Kiefer, Claus; Lämmerzahl, Claus
2003-01-01
The relation between quantum theory and the theory of gravitation remains one of the most outstanding unresolved issues of modern physics. According to general expectation, general relativity as well as quantum (field) theory in a fixed background spacetime cannot be fundamentally correct. Hence there should exist a broader theory comprising both in appropriate limits, i.e., quantum gravity. This book gives readers a comprehensive introduction accessible to interested non-experts to the main issues surrounding the search for quantum gravity. These issues relate to fundamental questions concerning the various formalisms of quantization; specific questions concerning concrete processes, like gravitational collapse or black-hole evaporation; and the all important question concerning the possibility of experimental tests of quantum-gravity effects.
Experimental Joint Quantum Measurements with Minimum Uncertainty
Ringbauer, Martin; Biggerstaff, Devon N.; Broome, Matthew A.; Fedrizzi, Alessandro; Branciard, Cyril; White, Andrew G.
2014-01-01
Quantum physics constrains the accuracy of joint measurements of incompatible observables. Here we test tight measurement-uncertainty relations using single photons. We implement two independent, idealized uncertainty-estimation methods, the three-state method and the weak-measurement method, and adapt them to realistic experimental conditions. Exceptional quantum state fidelities of up to 0.999 98(6) allow us to verge upon the fundamental limits of measurement uncertainty.
Nonuniform code concatenation for universal fault-tolerant quantum computing
Nikahd, Eesa; Sedighi, Mehdi; Saheb Zamani, Morteza
2017-09-01
Using transversal gates is a straightforward and efficient technique for fault-tolerant quantum computing. Since transversal gates alone cannot be computationally universal, they must be combined with other approaches such as magic state distillation, code switching, or code concatenation to achieve universality. In this paper we propose an alternative approach for universal fault-tolerant quantum computing, mainly based on the code concatenation approach proposed in [T. Jochym-O'Connor and R. Laflamme, Phys. Rev. Lett. 112, 010505 (2014), 10.1103/PhysRevLett.112.010505], but in a nonuniform fashion. The proposed approach is described based on nonuniform concatenation of the 7-qubit Steane code with the 15-qubit Reed-Muller code, as well as the 5-qubit code with the 15-qubit Reed-Muller code, which lead to two 49-qubit and 47-qubit codes, respectively. These codes can correct any arbitrary single physical error with the ability to perform a universal set of fault-tolerant gates, without using magic state distillation.
Superconducting quantum simulator for topological order and the toric code
Sameti, Mahdi; Potočnik, Anton; Browne, Dan E.; Wallraff, Andreas; Hartmann, Michael J.
2017-04-01
Topological order is now being established as a central criterion for characterizing and classifying ground states of condensed matter systems and complements categorizations based on symmetries. Fractional quantum Hall systems and quantum spin liquids are receiving substantial interest because of their intriguing quantum correlations, their exotic excitations, and prospects for protecting stored quantum information against errors. Here, we show that the Hamiltonian of the central model of this class of systems, the toric code, can be directly implemented as an analog quantum simulator in lattices of superconducting circuits. The four-body interactions, which lie at its heart, are in our concept realized via superconducting quantum interference devices (SQUIDs) that are driven by a suitably oscillating flux bias. All physical qubits and coupling SQUIDs can be individually controlled with high precision. Topologically ordered states can be prepared via an adiabatic ramp of the stabilizer interactions. Strings of qubit operators, including the stabilizers and correlations along noncontractible loops, can be read out via a capacitive coupling to read-out resonators. Moreover, the available single-qubit operations allow to create and propagate elementary excitations of the toric code and to verify their fractional statistics. The architecture we propose allows to implement a large variety of many-body interactions and thus provides a versatile analog quantum simulator for topological order and lattice gauge theories.
Experimenters' Free Will and Quantum Certainty
Bisognano, Joseph J
2012-01-01
Physics has long lived with a schizophrenia that desires determinism for measured systems while demanding that experimenters decide what to measure on a whim. Intriguingly, such a free will assumption for experimenters has thwarted many attempts to provide a satisfactory explanation of how quantum probabilities evolve to clear-cut measurements. An overview of this quantum measurement problem is presented without equations, and the lesson is drawn that denial of experimenters' free will may be the only workable solutions. If the free will assumption is rejected, then a door is open that may ultimately reconcile quantum mechanics with the definiteness of individual experiments. A holistic view is offered for an Escher-like self-consistent space-time net of events rather than a conspiracy of initial conditions as a way forward.
Channel representation of quantum error-correcting codes
Energy Technology Data Exchange (ETDEWEB)
Guetschow, Johannes; Vogts, Holger; Werner, Reinhard [Institut fuer Mathematische Physik, TU Braunschweig (Germany)
2008-07-01
Quantum error-correcting codes (qeccs) are essential for most of the proposed realizations of quantum computation to correct errors due to decoherence. Quantum convolutional codes (qccs) are a promising candidate for on line encoding and decoding of a flow of quantum information thus enabling the sending party to begin with the transmission of quantum information before the end of the flow (or a block) is reached. Analogously the decoding process can begin before the end of the transmission. Until now, only the noise and interaction with the environment were described in the channel formalism. We investigate qeccs and describe their encoders as channels. Block encoders are represented by memoryless channels, whereas convolutional encoders are described by memory channels. Convolutional encoders need to be 'non-catastrophic', meaning an error on a single source qubit should only affect a finite number of target qubits. We investigate the relation between this condition and the 'forgetfulness'-property of quantum memory channels.
A new approach to codeword stabilized quantum codes using the algebraic structure of modules
Santiago, Douglas Frederico Guimarães; Otoni, Geraldo Samuel Sena
2015-01-01
In this work, we study the Codeword Stabilized Quantum Codes (CWS codes) a generalization of the stabilizers quantum codes using a new approach, the algebraic structure of modules, a generalization of linear spaces. We show then a new result that relates CWS codes with stabilizer codes generalizing results in the literature.
Quantum Experimental Data in Psychology and Economics
Aerts, Diederik; D'Hooghe, Bart; Haven, Emmanuel
2010-12-01
We prove a theorem which shows that a collection of experimental data of probabilistic weights related to decisions with respect to situations and their disjunction cannot be modeled within a classical probabilistic weight structure in case the experimental data contain the effect referred to as the ‘disjunction effect’ in psychology. We identify different experimental situations in psychology, more specifically in concept theory and in decision theory, and in economics (namely situations where Savage’s Sure-Thing Principle is violated) where the disjunction effect appears and we point out the common nature of the effect. We analyze how our theorem constitutes a no-go theorem for classical probabilistic weight structures for common experimental data when the disjunction effect is affecting the values of these data. We put forward a simple geometric criterion that reveals the non classicality of the considered probabilistic weights and we illustrate our geometrical criterion by means of experimentally measured membership weights of items with respect to pairs of concepts and their disjunctions. The violation of the classical probabilistic weight structure is very analogous to the violation of the well-known Bell inequalities studied in quantum mechanics. The no-go theorem we prove in the present article with respect to the collection of experimental data we consider has a status analogous to the well known no-go theorems for hidden variable theories in quantum mechanics with respect to experimental data obtained in quantum laboratories. Our analysis puts forward a strong argument in favor of the validity of using the quantum formalism for modeling the considered psychological experimental data as considered in this paper.
Experimentally exploring compressed sensing quantum tomography
Steffens, A.; Riofrío, C. A.; McCutcheon, W.; Roth, I.; Bell, B. A.; McMillan, A.; Tame, M. S.; Rarity, J. G.; Eisert, J.
2017-06-01
In the light of the progress in quantum technologies, the task of verifying the correct functioning of processes and obtaining accurate tomographic information about quantum states becomes increasingly important. Compressed sensing, a machinery derived from the theory of signal processing, has emerged as a feasible tool to perform robust and significantly more resource-economical quantum state tomography for intermediate-sized quantum systems. In this work, we provide a comprehensive analysis of compressed sensing tomography in the regime in which tomographically complete data is available with reliable statistics from experimental observations of a multi-mode photonic architecture. Due to the fact that the data is known with high statistical significance, we are in a position to systematically explore the quality of reconstruction depending on the number of employed measurement settings, randomly selected from the complete set of data, and on different model assumptions. We present and test a complete prescription to perform efficient compressed sensing and are able to reliably use notions of model selection and cross validation to account for experimental imperfections and finite counting statistics. Thus, we establish compressed sensing as an effective tool for quantum state tomography, specifically suited for photonic systems.
Tartarus: A relativistic Green's function quantum average atom code
Gill, N. M.; Starrett, C. E.
2017-09-01
A relativistic Green's Function quantum average atom model is implemented in the Tartarus code for the calculation of equation of state data in dense plasmas. We first present the relativistic extension of the quantum Green's Function average atom model described by Starrett [1]. The Green's Function approach addresses the numerical challenges arising from resonances in the continuum density of states without the need for resonance tracking algorithms or adaptive meshes, though there are still numerical challenges inherent to this algorithm. We discuss how these challenges are addressed in the Tartarus algorithm. The outputs of the calculation are shown in comparison to PIMC/DFT-MD simulations of the Principal Shock Hugoniot in Silicon. We also present the calculation of the Hugoniot for Silver coming from both the relativistic and nonrelativistic modes of the Tartarus code.
Effect of quantum fluctuation in error-correcting codes.
Otsubo, Yosuke; Inoue, Jun-ichi; Nagata, Kenji; Okada, Masato
2012-11-01
We discuss the decoding performance of error-correcting codes based on a model in which quantum fluctuations are introduced by means of a transverse field. The essential issue in this paper is whether quantum fluctuations improve the decoding quality compared with the conventional estimation based on thermal fluctuations, which is called finite-temperature decoding. We found that an estimation incorporating quantum fluctuations approaches the optimal performance of finite-temperature decoding. The results are illustrated by numerically solving saddle-point equations and performing a Monte Carlo simulation. We also evaluated the upper bound of the overlap between the original sequence and the decoded sequence derived from the equations of state for the order parameters, which is a measure of the decoding performance.
Experimental quantum digital signature over 102 km
Yin, Hua-Lei; Fu, Yao; Liu, Hui; Tang, Qi-Jie; Wang, Jian; You, Li-Xing; Zhang, Wei-Jun; Chen, Si-Jing; Wang, Zhen; Zhang, Qiang; Chen, Teng-Yun; Chen, Zeng-Bing; Pan, Jian-Wei
2017-03-01
Quantum digital signature (QDS) is an approach to guarantee the nonrepudiation, unforgeability, and transferability of a signature with information-theoretical security. Previous experimental realizations of QDS relied on an unrealistic assumption of secure channels and the longest distance is several kilometers. Here, we have experimentally demonstrated a recently proposed QDS protocol without assuming any secure channel. Exploiting the decoy state modulation, we have successfully signed a one-bit message through an up to 102-km optical fiber. Furthermore, we continuously run the system to sign the longer message "USTC" with 32 bits at the distance of 51 km. Our results pave the way towards the practical application of QDS.
Linear Plotkin bound for entanglement-assisted quantum codes
Guo, Luobin; Li, Ruihu
2013-03-01
The entanglement-assisted (EA) formalism is a generalization of the standard stabilizer formalism, and it can transform arbitrary quaternary classical linear codes into entanglement-assisted quantum error correcting codes (EAQECCs) by using of shared entanglement between the sender and the receiver. Using the special structure of linear EAQECCs, we derive an EA-Plotkin bound for linear EAQECCs, which strengthens the previous known EA-Plotkin bound. This linear EA-Plotkin bound is tighter then the EA-Singleton bound, and matches the EA-Hamming bound and the EA-linear programming bound in some cases. We also construct three families of EAQECCs with good parameters. Some of these EAQECCs saturate this linear EA-Plotkin bound and the others are near optimal according to this bound; almost all of these linear EAQECCs are degenerate codes.
Experimental quantum tossing of a single coin
Energy Technology Data Exchange (ETDEWEB)
Nguyen, A T [Service OPERA photonique, CP 194/5, Universite Libre de Bruxelles (ULB), Avenue F D Roosevelt 50, B-1050 Bruxelles (Belgium); Frison, J; Massar, S [Laboratoire dInformation Quantique, CP 225, Universite Libre de Bruxelles (ULB), Boulevard du Triomphe, B-1050 Bruxelles (Belgium); Huy, K Phan [Departement dOptique P M Duffieux, Institut FEMTO-ST, Centre National de la Recherche Scientifique UMR 6174, Universite de Franche-Comte, 25030 Besancon (France)], E-mail: annguyen@ulb.ac.be, E-mail: smassar@ulb.ac.be
2008-08-15
The cryptographic protocol of coin tossing consists of two parties, Alice and Bob, who do not trust each other, but want to generate a random bit. If the parties use a classical communication channel and have unlimited computational resources, one of them can always cheat perfectly. If the parties use a quantum communication channel, there exist protocols such that neither party can cheat perfectly, although they may be able to significantly bias the coin. Here, we analyze in detail how the performance of a quantum coin tossing experiment should be compared to classical protocols, taking into account the inevitable experimental imperfections. We then report an all-optical fiber experiment in which a single coin is tossed whose randomness is higher than achievable by any classical protocol and present some easily realizable cheating strategies by Alice and Bob.
Experimental quantum tossing of a single coin
Nguyen, A. T.; Frison, J.; Phan Huy, K.; Massar, S.
2008-08-01
The cryptographic protocol of coin tossing consists of two parties, Alice and Bob, who do not trust each other, but want to generate a random bit. If the parties use a classical communication channel and have unlimited computational resources, one of them can always cheat perfectly. If the parties use a quantum communication channel, there exist protocols such that neither party can cheat perfectly, although they may be able to significantly bias the coin. Here, we analyze in detail how the performance of a quantum coin tossing experiment should be compared to classical protocols, taking into account the inevitable experimental imperfections. We then report an all-optical fiber experiment in which a single coin is tossed whose randomness is higher than achievable by any classical protocol and present some easily realizable cheating strategies by Alice and Bob.
High-capacity quantum Fibonacci coding for key distribution
Simon, David S.; Lawrence, Nate; Trevino, Jacob; Dal Negro, Luca; Sergienko, Alexander V.
2013-03-01
Quantum cryptography and quantum key distribution (QKD) have been the most successful applications of quantum information processing, highlighting the unique capability of quantum mechanics, through the no-cloning theorem, to securely share encryption keys between two parties. Here, we present an approach to high-capacity, high-efficiency QKD by exploiting cross-disciplinary ideas from quantum information theory and the theory of light scattering of aperiodic photonic media. We propose a unique type of entangled-photon source, as well as a physical mechanism for efficiently sharing keys. The key-sharing protocol combines entanglement with the mathematical properties of a recursive sequence to allow a realization of the physical conditions necessary for implementation of the no-cloning principle for QKD, while the source produces entangled photons whose orbital angular momenta (OAM) are in a superposition of Fibonacci numbers. The source is used to implement a particular physical realization of the protocol by randomly encoding the Fibonacci sequence onto entangled OAM states, allowing secure generation of long keys from few photons. Unlike in polarization-based protocols, reference frame alignment is unnecessary, while the required experimental setup is simpler than other OAM-based protocols capable of achieving the same capacity and its complexity grows less rapidly with increasing range of OAM used.
Extremal quantum correlations: Experimental study with two-qubit states
Energy Technology Data Exchange (ETDEWEB)
Chiuri, A.; Mataloni, P. [Dipartimento di Fisica, Sapienza Universita di Roma, Piazzale Aldo Moro 5, I-00185 Roma (Italy); Istituto Nazionale di Ottica (INO-CNR), L.go E. Fermi 6, I-50125 Firenze (Italy); Vallone, G. [Dipartimento di Fisica, Sapienza Universita di Roma, Piazzale Aldo Moro 5, I-00185 Roma (Italy); Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi, Via Panisperna 89/A, Compendio del Viminale, I-00184 Roma (Italy); Paternostro, M. [Centre for Theoretical Atomic, Molecular, and Optical Physics, School of Mathematics and Physics, Queen' s University, Belfast BT7 1NN (United Kingdom)
2011-08-15
We explore experimentally the space of two-qubit quantum-correlated mixed states, including frontier states as defined by the use of quantum discord and von Neumann entropy. Our experimental setup is flexible enough to allow for high-quality generation of a vast variety of states. We address quantitatively the relation between quantum discord and a recently suggested alternative measure of quantum correlations.
Optimal quantum error correcting codes from absolutely maximally entangled states
Raissi, Zahra; Gogolin, Christian; Riera, Arnau; Acín, Antonio
2018-02-01
Absolutely maximally entangled (AME) states are pure multi-partite generalizations of the bipartite maximally entangled states with the property that all reduced states of at most half the system size are in the maximally mixed state. AME states are of interest for multipartite teleportation and quantum secret sharing and have recently found new applications in the context of high-energy physics in toy models realizing the AdS/CFT-correspondence. We work out in detail the connection between AME states of minimal support and classical maximum distance separable (MDS) error correcting codes and, in particular, provide explicit closed form expressions for AME states of n parties with local dimension \
The cosmic code quantum physics as the language of nature
Pagels, Heinz R
2012-01-01
""The Cosmic Code can be read by anyone. I heartily recommend it!"" - The New York Times Book Review""A reliable guide for the nonmathematical reader across the highest ridges of physical theory. Pagels is unfailingly lighthearted and confident."" - Scientific American""A sound, clear, vital work that deserves the attention of anyone who takes an interest in the relationship between material reality and the human mind."" - Science 82This is one of the most important books on quantum mechanics ever written for general readers. Heinz Pagels, an eminent physicist and science writer, discusses and
Complementarity between entanglement-assisted and quantum distributed random access code
Hameedi, Alley; Saha, Debashis; Mironowicz, Piotr; Pawłowski, Marcin; Bourennane, Mohamed
2017-05-01
Collaborative communication tasks such as random access codes (RACs) employing quantum resources have manifested great potential in enhancing information processing capabilities beyond the classical limitations. The two quantum variants of RACs, namely, quantum random access code (QRAC) and the entanglement-assisted random access code (EARAC), have demonstrated equal prowess for a number of tasks. However, there do exist specific cases where one outperforms the other. In this article, we study a family of 3 →1 distributed RACs [J. Bowles, N. Brunner, and M. Pawłowski, Phys. Rev. A 92, 022351 (2015), 10.1103/PhysRevA.92.022351] and present its general construction of both the QRAC and the EARAC. We demonstrate that, depending on the function of inputs that is sought, if QRAC achieves the maximal success probability then EARAC fails to do so and vice versa. Moreover, a tripartite Bell-type inequality associated with the EARAC variants reveals the genuine multipartite nonlocality exhibited by our protocol. We conclude with an experimental realization of the 3 →1 distributed QRAC that achieves higher success probabilities than the maximum possible with EARACs for a number of tasks.
Quantum adiabatic algorithm for factorization and its experimental implementation.
Peng, Xinhua; Liao, Zeyang; Xu, Nanyang; Qin, Gan; Zhou, Xianyi; Suter, Dieter; Du, Jiangfeng
2008-11-28
We propose an adiabatic quantum algorithm capable of factorizing numbers, using fewer qubits than Shor's algorithm. We implement the algorithm in a NMR quantum information processor and experimentally factorize the number 21. In the range that our classical computer could simulate, the quantum adiabatic algorithm works well, providing evidence that the running time of this algorithm scales polynomially with the problem size.
Experimental demonstration of entanglement assisted coding using a two-mode squeezed vacuum state
Mizuno, Jun; Wakui, Kentaro; Furusawa, Akira; Sasaki, Masahide
2004-01-01
We have experimentally realized the scheme initially proposed as quantum dense coding with continuous variables [Ban, J. Opt. B \\textbf{1}, L9 (1999), and Braunstein and Kimble, \\pra\\textbf{61}, 042302 (2000)]. In our experiment, a pair of EPR (Einstein-Podolski-Rosen) beams is generated from two independent squeezed vacua. After adding two-quadrature signal to one of the EPR beams, two squeezed beams that contain the signal were recovered. Although our squeezing level is not sufficient to de...
Experimental realization of quantum zeno dynamics.
Schäfer, F; Herrera, I; Cherukattil, S; Lovecchio, C; Cataliotti, F S; Caruso, F; Smerzi, A
2014-01-01
It is generally impossible to probe a quantum system without disturbing it. However, it is possible to exploit the back action of quantum measurements and strong couplings to tailor and protect the coherent evolution of a quantum system. This is a profound and counterintuitive phenomenon known as quantum Zeno dynamics. Here we demonstrate quantum Zeno dynamics with a rubidium Bose-Einstein condensate in a five-level Hilbert space. We harness measurements and strong couplings to dynamically disconnect different groups of quantum states and constrain the atoms to coherently evolve inside a two-level subregion. In parallel to the foundational importance due to the realization of a dynamical superselection rule and the theory of quantum measurements, this is an important step forward in protecting and controlling quantum dynamics and, broadly speaking, quantum information processing.
Scalable Quantum Circuit and Control for a Superconducting Surface Code
Versluis, R.; Poletto, S.; Khammassi, N.; Tarasinski, B.; Haider, N.; Michalak, D. J.; Bruno, A.; Bertels, K.; DiCarlo, L.
2017-09-01
We present a scalable scheme for executing the error-correction cycle of a monolithic surface-code fabric composed of fast-flux-tunable transmon qubits with nearest-neighbor coupling. An eight-qubit unit cell forms the basis for repeating both the quantum hardware and coherent control, enabling spatial multiplexing. This control uses three fixed frequencies for all single-qubit gates and a unique frequency-detuning pattern for each qubit in the cell. By pipelining the interaction and readout steps of ancilla-based X - and Z -type stabilizer measurements, we can engineer detuning patterns that avoid all second-order transmon-transmon interactions except those exploited in controlled-phase gates, regardless of fabric size. Our scheme is applicable to defect-based and planar logical qubits, including lattice surgery.
FPGA based digital phase-coding quantum key distribution system
Lu, XiaoMing; Zhang, LiJun; Wang, YongGang; Chen, Wei; Huang, DaJun; Li, Deng; Wang, Shuang; He, DeYong; Yin, ZhenQiang; Zhou, Yu; Hui, Cong; Han, ZhengFu
2015-12-01
Quantum key distribution (QKD) is a technology with the potential capability to achieve information-theoretic security. Phasecoding is an important approach to develop practical QKD systems in fiber channel. In order to improve the phase-coding modulation rate, we proposed a new digital-modulation method in this paper and constructed a compact and robust prototype of QKD system using currently available components in our lab to demonstrate the effectiveness of the method. The system was deployed in laboratory environment over a 50 km fiber and continuously operated during 87 h without manual interaction. The quantum bit error rate (QBER) of the system was stable with an average value of 3.22% and the secure key generation rate is 8.91 kbps. Although the modulation rate of the photon in the demo system was only 200 MHz, which was limited by the Faraday-Michelson interferometer (FMI) structure, the proposed method and the field programmable gate array (FPGA) based electronics scheme have a great potential for high speed QKD systems with Giga-bits/second modulation rate.
New Class of Quantum Error-Correcting Codes for a Bosonic Mode
Michael, Marios H.; Silveri, Matti; Brierley, R. T.; Albert, Victor V.; Salmilehto, Juha; Jiang, Liang; Girvin, S. M.
2016-07-01
We construct a new class of quantum error-correcting codes for a bosonic mode, which are advantageous for applications in quantum memories, communication, and scalable computation. These "binomial quantum codes" are formed from a finite superposition of Fock states weighted with binomial coefficients. The binomial codes can exactly correct errors that are polynomial up to a specific degree in bosonic creation and annihilation operators, including amplitude damping and displacement noise as well as boson addition and dephasing errors. For realistic continuous-time dissipative evolution, the codes can perform approximate quantum error correction to any given order in the time step between error detection measurements. We present an explicit approximate quantum error recovery operation based on projective measurements and unitary operations. The binomial codes are tailored for detecting boson loss and gain errors by means of measurements of the generalized number parity. We discuss optimization of the binomial codes and demonstrate that by relaxing the parity structure, codes with even lower unrecoverable error rates can be achieved. The binomial codes are related to existing two-mode bosonic codes, but offer the advantage of requiring only a single bosonic mode to correct amplitude damping as well as the ability to correct other errors. Our codes are similar in spirit to "cat codes" based on superpositions of the coherent states but offer several advantages such as smaller mean boson number, exact rather than approximate orthonormality of the code words, and an explicit unitary operation for repumping energy into the bosonic mode. The binomial quantum codes are realizable with current superconducting circuit technology, and they should prove useful in other quantum technologies, including bosonic quantum memories, photonic quantum communication, and optical-to-microwave up- and down-conversion.
Experimental Bayesian Quantum Phase Estimation on a Silicon Photonic Chip.
Paesani, S; Gentile, A A; Santagati, R; Wang, J; Wiebe, N; Tew, D P; O'Brien, J L; Thompson, M G
2017-03-10
Quantum phase estimation is a fundamental subroutine in many quantum algorithms, including Shor's factorization algorithm and quantum simulation. However, so far results have cast doubt on its practicability for near-term, nonfault tolerant, quantum devices. Here we report experimental results demonstrating that this intuition need not be true. We implement a recently proposed adaptive Bayesian approach to quantum phase estimation and use it to simulate molecular energies on a silicon quantum photonic device. The approach is verified to be well suited for prethreshold quantum processors by investigating its superior robustness to noise and decoherence compared to the iterative phase estimation algorithm. This shows a promising route to unlock the power of quantum phase estimation much sooner than previously believed.
Experimental realization of quantum cheque using a five-qubit quantum computer
Behera, Bikash K.; Banerjee, Anindita; Panigrahi, Prasanta K.
2017-12-01
Quantum cheques could be a forgery-free way to make transaction in a quantum networked banking system with perfect security against any no-signalling adversary. Here, we demonstrate the implementation of quantum cheque, proposed by Moulick and Panigrahi (Quantum Inf Process 15:2475-2486, 2016), using the five-qubit IBM quantum computer. Appropriate single qubit, CNOT and Fredkin gates are used in an optimized configuration. The accuracy of implementation is checked and verified through quantum state tomography by comparing results from the theoretical and experimental density matrices.
Rutkowski, Adam; Buraczewski, Adam; Horodecki, Paweł; Stobińska, Magdalena
2017-01-13
Quantum steering is a relatively simple test for proving that the values of quantum-mechanical measurement outcomes come into being only in the act of measurement. By exploiting quantum correlations, Alice can influence-steer-Bob's physical system in a way that is impossible in classical mechanics, as shown by the violation of steering inequalities. Demonstrating this and similar quantum effects for systems of increasing size, approaching even the classical limit, is a long-standing challenging problem. Here, we prove an experimentally feasible unbounded violation of a steering inequality. We derive its universal form where tolerance for measurement-setting errors is explicitly built in by means of the Deutsch-Maassen-Uffink entropic uncertainty relation. Then, generalizing the mutual unbiasedness, we apply the inequality to the multisinglet and multiparticle bipartite Bell state. However, the method is general and opens the possibility of employing multiparticle bipartite steering for randomness certification and development of quantum technologies, e.g., random access codes.
Density-matrix simulation of small surface codes under current and projected experimental noise
O'Brien, T. E.; Tarasinski, B.; DiCarlo, L.
2017-09-01
We present a density-matrix simulation of the quantum memory and computing performance of the distance-3 logical qubit Surface-17, following a recently proposed quantum circuit and using experimental error parameters for transmon qubits in a planar circuit QED architecture. We use this simulation to optimize components of the QEC scheme (e.g., trading off stabilizer measurement infidelity for reduced cycle time) and to investigate the benefits of feedback harnessing the fundamental asymmetry of relaxation-dominated error in the constituent transmons. A lower-order approximate calculation extends these predictions to the distance-5 Surface-49. These results clearly indicate error rates below the fault-tolerance threshold of the surface code, and the potential for Surface-17 to perform beyond the break-even point of quantum memory. However, Surface-49 is required to surpass the break-even point of computation at state-of-the-art qubit relaxation times and readout speeds.
Experimental QR code optical encryption: noise-free data recovering.
Barrera, John Fredy; Mira-Agudelo, Alejandro; Torroba, Roberto
2014-05-15
We report, to our knowledge for the first time, the experimental implementation of a quick response (QR) code as a "container" in an optical encryption system. A joint transform correlator architecture in an interferometric configuration is chosen as the experimental scheme. As the implementation is not possible in a single step, a multiplexing procedure to encrypt the QR code of the original information is applied. Once the QR code is correctly decrypted, the speckle noise present in the recovered QR code is eliminated by a simple digital procedure. Finally, the original information is retrieved completely free of any kind of degradation after reading the QR code. Additionally, we propose and implement a new protocol in which the reception of the encrypted QR code and its decryption, the digital block processing, and the reading of the decrypted QR code are performed employing only one device (smartphone, tablet, or computer). The overall method probes to produce an outcome far more attractive to make the adoption of the technique a plausible option. Experimental results are presented to demonstrate the practicality of the proposed security system.
New Class of Quantum Error-Correcting Codes for a Bosonic Mode
Directory of Open Access Journals (Sweden)
Marios H. Michael
2016-07-01
Full Text Available We construct a new class of quantum error-correcting codes for a bosonic mode, which are advantageous for applications in quantum memories, communication, and scalable computation. These “binomial quantum codes” are formed from a finite superposition of Fock states weighted with binomial coefficients. The binomial codes can exactly correct errors that are polynomial up to a specific degree in bosonic creation and annihilation operators, including amplitude damping and displacement noise as well as boson addition and dephasing errors. For realistic continuous-time dissipative evolution, the codes can perform approximate quantum error correction to any given order in the time step between error detection measurements. We present an explicit approximate quantum error recovery operation based on projective measurements and unitary operations. The binomial codes are tailored for detecting boson loss and gain errors by means of measurements of the generalized number parity. We discuss optimization of the binomial codes and demonstrate that by relaxing the parity structure, codes with even lower unrecoverable error rates can be achieved. The binomial codes are related to existing two-mode bosonic codes, but offer the advantage of requiring only a single bosonic mode to correct amplitude damping as well as the ability to correct other errors. Our codes are similar in spirit to “cat codes” based on superpositions of the coherent states but offer several advantages such as smaller mean boson number, exact rather than approximate orthonormality of the code words, and an explicit unitary operation for repumping energy into the bosonic mode. The binomial quantum codes are realizable with current superconducting circuit technology, and they should prove useful in other quantum technologies, including bosonic quantum memories, photonic quantum communication, and optical-to-microwave up- and down-conversion.
Quantum Gravity Mathematical Models and Experimental Bounds
Fauser, Bertfried; Zeidler, Eberhard
2007-01-01
The construction of a quantum theory of gravity is the most fundamental challenge confronting contemporary theoretical physics. The different physical ideas which evolved while developing a theory of quantum gravity require highly advanced mathematical methods. This book presents different mathematical approaches to formulate a theory of quantum gravity. It represents a carefully selected cross-section of lively discussions about the issue of quantum gravity which took place at the second workshop "Mathematical and Physical Aspects of Quantum Gravity" in Blaubeuren, Germany. This collection covers in a unique way aspects of various competing approaches. A unique feature of the book is the presentation of different approaches to quantum gravity making comparison feasible. This feature is supported by an extensive index. The book is mainly addressed to mathematicians and physicists who are interested in questions related to mathematical physics. It allows the reader to obtain a broad and up-to-date overview on ...
Experimental comparison of two quantum computing architectures.
Linke, Norbert M; Maslov, Dmitri; Roetteler, Martin; Debnath, Shantanu; Figgatt, Caroline; Landsman, Kevin A; Wright, Kenneth; Monroe, Christopher
2017-03-28
We run a selection of algorithms on two state-of-the-art 5-qubit quantum computers that are based on different technology platforms. One is a publicly accessible superconducting transmon device (www. ibm.com/ibm-q) with limited connectivity, and the other is a fully connected trapped-ion system. Even though the two systems have different native quantum interactions, both can be programed in a way that is blind to the underlying hardware, thus allowing a comparison of identical quantum algorithms between different physical systems. We show that quantum algorithms and circuits that use more connectivity clearly benefit from a better-connected system of qubits. Although the quantum systems here are not yet large enough to eclipse classical computers, this experiment exposes critical factors of scaling quantum computers, such as qubit connectivity and gate expressivity. In addition, the results suggest that codesigning particular quantum applications with the hardware itself will be paramount in successfully using quantum computers in the future.
Single-shot secure quantum network coding on butterfly network with free public communication
Owari, Masaki; Kato, Go; Hayashi, Masahito
2018-01-01
Quantum network coding on the butterfly network has been studied as a typical example of quantum multiple cast network. We propose a secure quantum network code for the butterfly network with free public classical communication in the multiple unicast setting under restricted eavesdropper’s power. This protocol certainly transmits quantum states when there is no attack. We also show the secrecy with shared randomness as additional resource when the eavesdropper wiretaps one of the channels in the butterfly network and also derives the information sending through public classical communication. Our protocol does not require verification process, which ensures single-shot security.
Experimental demonstration of nonbilocal quantum correlations.
Saunders, Dylan J; Bennet, Adam J; Branciard, Cyril; Pryde, Geoff J
2017-04-01
Quantum mechanics admits correlations that cannot be explained by local realistic models. The most studied models are the standard local hidden variable models, which satisfy the well-known Bell inequalities. To date, most works have focused on bipartite entangled systems. We consider correlations between three parties connected via two independent entangled states. We investigate the new type of so-called "bilocal" models, which correspondingly involve two independent hidden variables. These models describe scenarios that naturally arise in quantum networks, where several independent entanglement sources are used. Using photonic qubits, we build such a linear three-node quantum network and demonstrate nonbilocal correlations by violating a Bell-like inequality tailored for bilocal models. Furthermore, we show that the demonstration of nonbilocality is more noise-tolerant than that of standard Bell nonlocality in our three-party quantum network.
Perfect quantum multiple-unicast network coding protocol
Li, Dan-Dan; Gao, Fei; Qin, Su-Juan; Wen, Qiao-Yan
2018-01-01
In order to realize long-distance and large-scale quantum communication, it is natural to utilize quantum repeater. For a general quantum multiple-unicast network, it is still puzzling how to complete communication tasks perfectly with less resources such as registers. In this paper, we solve this problem. By applying quantum repeaters to multiple-unicast communication problem, we give encoding-decoding schemes for source nodes, internal ones and target ones, respectively. Source-target nodes share EPR pairs by using our encoding-decoding schemes over quantum multiple-unicast network. Furthermore, quantum communication can be accomplished perfectly via teleportation. Compared with existed schemes, our schemes can reduce resource consumption and realize long-distance transmission of quantum information.
Experimental realization of Shor's quantum factoring algorithm using nuclear magnetic resonance.
Vandersypen, L M; Steffen, M; Breyta, G; Yannoni, C S; Sherwood, M H; Chuang, I L
The number of steps any classical computer requires in order to find the prime factors of an l-digit integer N increases exponentially with l, at least using algorithms known at present. Factoring large integers is therefore conjectured to be intractable classically, an observation underlying the security of widely used cryptographic codes. Quantum computers, however, could factor integers in only polynomial time, using Shor's quantum factoring algorithm. Although important for the study of quantum computers, experimental demonstration of this algorithm has proved elusive. Here we report an implementation of the simplest instance of Shor's algorithm: factorization of N = 15 (whose prime factors are 3 and 5). We use seven spin-1/2 nuclei in a molecule as quantum bits, which can be manipulated with room temperature liquid-state nuclear magnetic resonance techniques. This method of using nuclei to store quantum information is in principle scalable to systems containing many quantum bits, but such scalability is not implied by the present work. The significance of our work lies in the demonstration of experimental and theoretical techniques for precise control and modelling of complex quantum computers. In particular, we present a simple, parameter-free but predictive model of decoherence effects in our system.
Experimental Realization of a Quantum Spin Pump
DEFF Research Database (Denmark)
Watson, Susan; Potok, R.; M. Marcus, C.
2003-01-01
We demonstrate the operation of a quantum spin pump based on cyclic radio-frequency excitation of a GaAs quantum dot, including the ability to pump pure spin without pumping charge. The device takes advantage of bidirectional mesoscopic fluctuations of pumped current, made spin......-dependent by the application of an in-plane Zeeman field. Spin currents are measured by placing the pump in a focusing geometry with a spin-selective collector....
The two-qubit amplitude damping channel: Characterization using quantum stabilizer codes
Energy Technology Data Exchange (ETDEWEB)
Omkar, S. [School of Physics, IISER TVM, CET Campus, Thiruvananthapuram 695016, Kerala (India); Srikanth, R., E-mail: srik@poornaprajna.org [Poornaprajna Institute of Scientific Research, Sadashivnagar, Bengaluru- 560080 (India); Banerjee, Subhashish [Indian Institute of Technology Rajasthan, Jodhpur- 342011 (India); Shaji, Anil [School of Physics, IISER TVM, CET Campus, Thiruvananthapuram 695016, Kerala (India)
2016-10-15
A protocol based on quantum error correction based characterization of quantum dynamics (QECCD) is developed for quantum process tomography on a two-qubit system interacting dissipatively with a vacuum bath. The method uses a 5-qubit quantum error correcting code that corrects arbitrary errors on the first two qubits, and also saturates the quantum Hamming bound. The dissipative interaction with a vacuum bath allows for both correlated and independent noise on the two-qubit system. We study the dependence of the degree of the correlation of the noise on evolution time and inter-qubit separation.
The two-qubit amplitude damping channel: Characterization using quantum stabilizer codes
Omkar, S.; Srikanth, R.; Banerjee, Subhashish; Shaji, Anil
2016-10-01
A protocol based on quantum error correction based characterization of quantum dynamics (QECCD) is developed for quantum process tomography on a two-qubit system interacting dissipatively with a vacuum bath. The method uses a 5-qubit quantum error correcting code that corrects arbitrary errors on the first two qubits, and also saturates the quantum Hamming bound. The dissipative interaction with a vacuum bath allows for both correlated and independent noise on the two-qubit system. We study the dependence of the degree of the correlation of the noise on evolution time and inter-qubit separation.
Experimental violation of local causality in a quantum network
Carvacho, Gonzalo; Andreoli, Francesco; Santodonato, Luca; Bentivegna, Marco; Chaves, Rafael; Sciarrino, Fabio
2017-03-01
Bell's theorem plays a crucial role in quantum information processing and thus several experimental investigations of Bell inequalities violations have been carried out over the years. Despite their fundamental relevance, however, previous experiments did not consider an ingredient of relevance for quantum networks: the fact that correlations between distant parties are mediated by several, typically independent sources. Here, using a photonic setup, we investigate a quantum network consisting of three spatially separated nodes whose correlations are mediated by two distinct sources. This scenario allows for the emergence of the so-called non-bilocal correlations, incompatible with any local model involving two independent hidden variables. We experimentally witness the emergence of this kind of quantum correlations by violating a Bell-like inequality under the fair-sampling assumption. Our results provide a proof-of-principle experiment of generalizations of Bell's theorem for networks, which could represent a potential resource for quantum communication protocols.
Experimental violation of local causality in a quantum network
Carvacho, Gonzalo; Andreoli, Francesco; Santodonato, Luca; Bentivegna, Marco; Chaves, Rafael; Sciarrino, Fabio
2017-01-01
Bell's theorem plays a crucial role in quantum information processing and thus several experimental investigations of Bell inequalities violations have been carried out over the years. Despite their fundamental relevance, however, previous experiments did not consider an ingredient of relevance for quantum networks: the fact that correlations between distant parties are mediated by several, typically independent sources. Here, using a photonic setup, we investigate a quantum network consisting of three spatially separated nodes whose correlations are mediated by two distinct sources. This scenario allows for the emergence of the so-called non-bilocal correlations, incompatible with any local model involving two independent hidden variables. We experimentally witness the emergence of this kind of quantum correlations by violating a Bell-like inequality under the fair-sampling assumption. Our results provide a proof-of-principle experiment of generalizations of Bell's theorem for networks, which could represent a potential resource for quantum communication protocols. PMID:28300068
Frames, designs, and spherical codes in quantum information theory
Renes, Joseph M.
Frame theory offers a lens through which to view a large portion of quantum information theory, providing an organizational principle to those topics in its purview. In this thesis, I cut a trail from foundational questions to practical applications, from the origin of the quantum probability rule to quantum cryptography, by way of a standard quantum measurement helpful in quantum tomography and representation of quantum theory. Before embarking, preparations are undertaken by outlining the relevant aspects of frame theory, particularly the characterization of generalized orthonormal bases in terms of physical quantum measurements, as well as several aesthetically appealing families of measurements, each possessing a high degree of symmetry. Much more than just elegant, though, these quantum measurements are found to be useful in many aspects of quantum information theory. I first consider the foundational question of justifying the quantum probability rule, showing that putting a probability valuation on generalized quantum measurements leads directly to the Born rule. Moreover, for qubits, the case neglected in the traditional formulation of Gleason's theorem, a symmetric three-outcome measurement called the trine is sufficient to impel the desired form. Keeping with foundational questions, I then turn to the problem of establishing a symmetric measurement capable of effortlessly rendering quantum theory in terms of classical probability theory. Numerical results provide an almost utterly convincing amount of evidence for this, justifying the subsequent study of its use in quantum tomography and detailed account of the properties of the reduction to probabilistic terms. Saving perhaps the most exciting topic for last, I make use of these aesthetic ensembles in the applied field of quantum cryptography. A large class of streamlined key distribution protocols may be cut from the cloth of these ensembles, and their symmetry affords them improved tolerance to
Experimental observation of quantum corrections to electrical ...
Indian Academy of Sciences (India)
X-ray diffraction patterns of nanocrystalline Fe–Cu–Nb–Si–B (FINEMET) alloys reveal that bcc -Fe/-FeSi crystallites with the average grain size of 20(5) nm are dispersed in amorphous matrix. Enhanced electron–electron interaction (EEI) and quantum interference (QI) effects as well as electron–magnon (and/or ...
Experimental determination of the degree of polarization of quantum states
DEFF Research Database (Denmark)
Kothe-Termén, Christian; Madsen, Lars Skovgaard; Andersen, Ulrik Lund
2013-01-01
We demonstrate experimental excitation-manifold-resolved polarization characterization of quantum states of light ranging from the few-photon to the many-photon level. In contrast to the traditional characterization of polarization that is based on the Stokes parameters, we experimentally determi...
Superconducting quantum circuits at the surface code threshold for fault tolerance.
Barends, R; Kelly, J; Megrant, A; Veitia, A; Sank, D; Jeffrey, E; White, T C; Mutus, J; Fowler, A G; Campbell, B; Chen, Y; Chen, Z; Chiaro, B; Dunsworth, A; Neill, C; O'Malley, P; Roushan, P; Vainsencher, A; Wenner, J; Korotkov, A N; Cleland, A N; Martinis, John M
2014-04-24
A quantum computer can solve hard problems, such as prime factoring, database searching and quantum simulation, at the cost of needing to protect fragile quantum states from error. Quantum error correction provides this protection by distributing a logical state among many physical quantum bits (qubits) by means of quantum entanglement. Superconductivity is a useful phenomenon in this regard, because it allows the construction of large quantum circuits and is compatible with microfabrication. For superconducting qubits, the surface code approach to quantum computing is a natural choice for error correction, because it uses only nearest-neighbour coupling and rapidly cycled entangling gates. The gate fidelity requirements are modest: the per-step fidelity threshold is only about 99 per cent. Here we demonstrate a universal set of logic gates in a superconducting multi-qubit processor, achieving an average single-qubit gate fidelity of 99.92 per cent and a two-qubit gate fidelity of up to 99.4 per cent. This places Josephson quantum computing at the fault-tolerance threshold for surface code error correction. Our quantum processor is a first step towards the surface code, using five qubits arranged in a linear array with nearest-neighbour coupling. As a further demonstration, we construct a five-qubit Greenberger-Horne-Zeilinger state using the complete circuit and full set of gates. The results demonstrate that Josephson quantum computing is a high-fidelity technology, with a clear path to scaling up to large-scale, fault-tolerant quantum circuits.
Trinity Multiscale Transport Code Development for Experimental Comparison
Highcock, E.; Barnes, M.; Colyer, G.; Citrin, J.; Dickinson, D.; Mandel, N.; van Wyk, F.; Roach, C.; Schekochihin, A.; Dorland, W.
2014-10-01
The Trinity multiscale transport code has been extensively upgraded to further its use in experimental comparison. The upgrades to Trinity have extended its capability to work with experimental data, allowed it to evolve the magnetic equilibrium self-consistently (at fixed current) and significantly enhanced the range and performance of its turbulent transport modeling options. To enhance its capability to reproduce experiment, Trinity is now able to take output from the CRONOS integrated modelling suite, which is able to provide high quality reconstructions of experimental equilibria of, for example, JET. Trinity has also been integrated with the CHEASE Grad-Shafranov code. This allows the magnetic equilibrium to be re-computed self consistently as the pressure gradient evolves. Trinity has been given new options for modeling turbulent transport. These include the well-known TGLF framework, and the newly developed GPU-based nonlinear code GRYFX. These will allow rapid initial scans with Trinity before more detailed gyrokinetic modeling. Trinity's performance will benefit from an extensive programme to upgrade one of its primary gyrokinetic turbulence modeling options, GS2. We present a summary of these improvements and preliminary results. This work was supported by STFC and the Culham Centre for Fusion Energy. Computing time was provided by IFERC grants MULTEI and GKDELB, The Hartree Centre, and EPSRC Grants EP/H002081/1 and EP/L000237/1.
Multiple-valued logic-protected coding for an optical non-quantum communication line
Antipov, A. L.; Bykovsky, A. Yu.; Vasiliev, N. A.; Egorov, A. A.
2006-01-01
A simple and cheap method of secret coding in an optical line is proposed based on multiple-valued logic. This method is shown to have very high cryptography resources and is designated for bidirectional information exchange in a team of mobile robots, where quantum teleportation coding cannot yet
Experimental demonstration of a programmable quantum computer by NMR.
Kim, Jaehyun; Lee, Jae-Seung; Hwang, Taesoon; Lee, Soonchil
2004-01-01
A programmable quantum computer is experimentally demonstrated by nuclear magnetic resonance using one qubit for the program and two qubits for data. A non-separable two-qubit operation is performed in a programmable way to show the successful demonstration. Projective measurements required in the programmable quantum computer are simulated by averaging the results of experiments just like when producing an effective pure state.
Provably Secure Experimental Quantum Bit-String Generation
Lamoureux, L. P.; Brainis, E.; Amans, D.; Barrett, J.; Massar, S.
2005-02-01
Coin tossing is a cryptographic task in which two parties who do not trust each other aim to generate a common random bit. Using classical communication this is impossible, but nontrivial coin tossing is possible using quantum communication. Here we consider the case when the parties do not want to toss a single coin, but many. This is called bit-string generation. We report the experimental generation of strings of coins which are provably more random than achievable using classical communication. The experiment is based on the “plug and play” scheme developed for quantum cryptography, and therefore well suited for long distance quantum communication.
Energy Technology Data Exchange (ETDEWEB)
Kronenberg, S.; Brucker, G.J.; Jordan, T.; Bechtel, E.; Gentner, F.; Groeber, E
2002-04-01
This paper reports the results of experiments that were designed to check the validity of the NOVICE Adjoint Monte Carlo Transport code in predicting emission-electron distributions from irradiated targets. Previous work demonstrated that the code accurately calculated total electron yields from irradiated targets. In this investigation, a gold target was irradiated by X-rays with effective quantum energies of 79, 127, 174, 216, and 250 keV. Spectra of electrons from the target were measured for an incident photon angle of 45 deg., an emission-electron polar angle of 45 deg., azimuthal angles of 0 deg. and 180 deg., and in both the forward and backward directions. NOVICE was used to predict those electron-energy-distributions for the same set of experimental conditions. The agreement in shape of the theoretical and experimental distributions was good, whereas the absolute agreement in amplitude was within about a factor of 2 over most of the energy range of the spectra. Previous experimental and theoretical comparisons together with these results show that the code can be used to simulate the generation physics of those distributions.
Superdense Coding with GHZ and Quantum Key Distribution with W in the ZX-calculus
Directory of Open Access Journals (Sweden)
Anne Hillebrand
2012-10-01
Full Text Available Quantum entanglement is a key resource in many quantum protocols, such as quantum teleportation and quantum cryptography. Yet entanglement makes protocols presented in Dirac notation difficult to verify. This is why Coecke and Duncan have introduced a diagrammatic language for quantum protocols, called the ZX-calculus. This diagrammatic notation is both intuitive and formally rigorous. It is a simple, graphical, high level language that emphasises the composition of systems and naturally captures the essentials of quantum mechanics. In the author's MSc thesis it has been shown for over 25 quantum protocols that the ZX-calculus provides a relatively easy and more intuitive presentation. Moreover, the author embarked on the task to apply categorical quantum mechanics on quantum security; earlier works did not touch anything but Bennett and Brassard's quantum key distribution protocol, BB84. Superdense coding with the Greenberger-Horne-Zeilinger state and quantum key distribution with the W-state are presented in the ZX-calculus in this paper.
Quantum image pseudocolor coding based on the density-stratified method
Jiang, Nan; Wu, Wenya; Wang, Luo; Zhao, Na
2015-05-01
Pseudocolor processing is a branch of image enhancement. It dyes grayscale images to color images to make the images more beautiful or to highlight some parts on the images. This paper proposes a quantum image pseudocolor coding scheme based on the density-stratified method which defines a colormap and changes the density value from gray to color parallel according to the colormap. Firstly, two data structures: quantum image GQIR and quantum colormap QCR are reviewed or proposed. Then, the quantum density-stratified algorithm is presented. Based on them, the quantum realization in the form of circuits is given. The main advantages of the quantum version for pseudocolor processing over the classical approach are that it needs less memory and can speed up the computation. Two kinds of examples help us to describe the scheme further. Finally, the future work are analyzed.
Experimental demonstration of macroscopic quantum coherence in Gaussian states
DEFF Research Database (Denmark)
Marquardt, C.; Andersen, Ulrik Lund; Leuchs, G.
2007-01-01
We witness experimentally the presence of macroscopic coherence in Gaussian quantum states using a recently proposed criterion [E. G. Cavalcanti and M. D. Reid, Phys. Rev. Lett. 97 170405 (2006)]. The macroscopic coherence stems from interference between macroscopically distinct states in phase...... space, and we prove experimentally that a coherent state contains these features with a distance in phase space of 0.51 +/- 0.02 shot noise units. This is surprising because coherent states are generally considered being at the border between classical and quantum states, not yet displaying any...
Experimental demonstration of squeezed-state quantum averaging
DEFF Research Database (Denmark)
Lassen, Mikael Østergaard; Madsen, Lars Skovgaard; Sabuncu, Metin
2010-01-01
We propose and experimentally demonstrate a universal quantum averaging process implementing the harmonic mean of quadrature variances. The averaged variances are prepared probabilistically by means of linear optical interference and measurement-induced conditioning. We verify that the implemented...... harmonic mean yields a lower value than the corresponding value obtained for the standard arithmetic-mean strategy. The effect of quantum averaging is experimentally tested for squeezed and thermal states as well as for uncorrelated and partially correlated noise sources. The harmonic-mean protocol can...
Experimental measurement-device-independent quantum digital signatures.
Roberts, G L; Lucamarini, M; Yuan, Z L; Dynes, J F; Comandar, L C; Sharpe, A W; Shields, A J; Curty, M; Puthoor, I V; Andersson, E
2017-10-23
The development of quantum networks will be paramount towards practical and secure telecommunications. These networks will need to sign and distribute information between many parties with information-theoretic security, requiring both quantum digital signatures (QDS) and quantum key distribution (QKD). Here, we introduce and experimentally realise a quantum network architecture, where the nodes are fully connected using a minimum amount of physical links. The central node of the network can act either as a totally untrusted relay, connecting the end users via the recently introduced measurement-device-independent (MDI)-QKD, or as a trusted recipient directly communicating with the end users via QKD. Using this network, we perform a proof-of-principle demonstration of QDS mediated by MDI-QKD. For that, we devised an efficient protocol to distil multiple signatures from the same block of data, thus reducing the statistical fluctuations in the sample and greatly enhancing the final QDS rate in the finite-size scenario.
QSPIN: A High Level Java API for Quantum Computing Experimentation
Barth, Tim
2017-01-01
QSPIN is a high level Java language API for experimentation in QC models used in the calculation of Ising spin glass ground states and related quadratic unconstrained binary optimization (QUBO) problems. The Java API is intended to facilitate research in advanced QC algorithms such as hybrid quantum-classical solvers, automatic selection of constraint and optimization parameters, and techniques for the correction and mitigation of model and solution errors. QSPIN includes high level solver objects tailored to the D-Wave quantum annealing architecture that implement hybrid quantum-classical algorithms [Booth et al.] for solving large problems on small quantum devices, elimination of variables via roof duality, and classical computing optimization methods such as GPU accelerated simulated annealing and tabu search for comparison. A test suite of documented NP-complete applications ranging from graph coloring, covering, and partitioning to integer programming and scheduling are provided to demonstrate current capabilities.
Construction of quantum caps in projective space PG( r, 4) and quantum codes of distance 4
Li, Ruihu; Fu, Qiang; Guo, Luobin; Li, Xueliang
2016-02-01
Constructions of quantum caps in projective space PG( r, 4) by recursive methods and computer search are discussed. For each even n satisfying n≥282 and each odd z satisfying z≥275, a quantum n-cap and a quantum z-cap in PG(k-1, 4) with suitable k are constructed, and [[n,n-2k,4
Entanglement-assisted codeword-stabilized quantum codes with imperfect ebits
Directory of Open Access Journals (Sweden)
Byungkyu Ahn
2016-06-01
Full Text Available In quantum communication systems, quantum error-correcting codes (QECCs are known to exhibit improved performance with the use of error-free entanglement bits (ebits. In practical situations, ebits inevitably suffer from errors, and as a result, the error-correcting capability of the code is diminished. Previous studies have proposed two different schemes as a solution. One study uses only one QECC to correct errors on the receiver side (i.e., Bob and sender side (i.e., Alice. The other uses different QECCs on each side. In this paper, we present a method to correct errors on both sides by using single nonadditive entanglement-assisted codeword stabilized quantum error-correcting code (EACWS QECC. We use the property that the number of effective error patterns decreases as much as the number of ebits. This property results in a greater number of logical codewords using the same number of physical qubits.
Modeling experimental plasma diagnostics in the FLASH code: proton radiography
Flocke, Norbert; Weide, Klaus; Feister, Scott; Tzeferacos, Petros; Lamb, Donald
2017-10-01
Proton radiography is an important diagnostic tool for laser plasma experiments and for studying magnetized plasmas. We describe a new synthetic proton radiography diagnostic recently implemented into the FLASH code. FLASH is an open source, finite-volume Eulerian, spatially adaptive radiation hydrodynamics and magneto-hydrodynamics code that incorporates capabilities for a broad range of physical processes. Proton radiography is modeled through the use of the (relativistic) Lorentz force equation governing the motion of protons through 3D domains. Both instantaneous (one time step) and time-resolved (over many time steps) proton radiography can be simulated. The code module is also equipped with several different setup options (beam structure and detector screen placements) to reproduce a large variety of experimental proton radiography designs. FLASH's proton radiography diagnostic unit can be used either during runtime or in post-processing of simulation results. FLASH is publicly available at flash.uchicago.edu. U.S. DOE NNSA, U.S. DOE NNSA ASC, U.S. DOE Office of Science and NSF.
Naghipour, Avaz; Jafarizadeh, Mohammad Ali
2017-12-01
This paper presents four classes of binary quantum codes with minimum distance 3 and 4, namely Class-I, Class-II, Class-III and Class-IV. The classes Class-I and Class-II are constructed based on self-dual orientable embeddings of the complete graphs K_{4r+1} and K_{4s} and by current graphs and rotation schemes. The parameters of two classes of quantum codes are [[2r(4r+1),2r(4r-3),3
NEAMS Experimental Support for Code Validation, INL FY2009
Energy Technology Data Exchange (ETDEWEB)
G. Youinou; G. Palmiotti; M. Salvatore; C. Rabiti
2009-09-01
The goal is for all modeling and simulation tools to be demonstrated accurate and reliable through a formal Verification and Validation (V&V) process, especially where such tools are to be used to establish safety margins and support regulatory compliance, or to design a system in a manner that reduces the role of expensive mockups and prototypes. Whereas the Verification part of the process does not rely on experiment, the Validation part, on the contrary, necessitates as many relevant and precise experimental data as possible to make sure the models reproduce reality as closely as possible. Hence, this report presents a limited selection of experimental data that could be used to validate the codes devoted mainly to Fast Neutron Reactor calculations in the US. Emphasis has been put on existing data for thermal-hydraulics, fuel and reactor physics. The principles of a new “smart” experiment that could be used to improve our knowledge of neutron cross-sections are presented as well. In short, it consists in irradiating a few milligrams of actinides and analyzing the results with Accelerator Mass Spectroscopy to infer the neutron cross-sections. Finally, the wealth of experimental data relevant to Fast Neutron Reactors in the US should not be taken for granted and efforts should be put on saving these 30-40 years old data and on making sure they are validation-worthy, i.e. that the experimental conditions and uncertainties are well documented.
Gao, Jian; Wang, Yongkang
2018-01-01
Structural properties of u-constacyclic codes over the ring F_p+u{F}_p are given, where p is an odd prime and u^2=1. Under a special Gray map from F_p+u{F}_p to F_p^2, some new non-binary quantum codes are obtained by this class of constacyclic codes.
Baianu,I C
2004-01-01
The concepts of quantum automata and quantum computation are studied in the context of quantum genetics and genetic networks with nonlinear dynamics. In previous publications (Baianu,1971a, b) the formal concept of quantum automaton and quantum computation, respectively, were introduced and their possible implications for genetic processes and metabolic activities in living cells and organisms were considered. This was followed by a report on quantum and abstract, symbolic computation based on the theory of categories, functors and natural transformations (Baianu,1971b; 1977; 1987; 2004; Baianu et al, 2004). The notions of topological semigroup, quantum automaton, or quantum computer, were then suggested with a view to their potential applications to the analogous simulation of biological systems, and especially genetic activities and nonlinear dynamics in genetic networks. Further, detailed studies of nonlinear dynamics in genetic networks were carried out in categories of n-valued, Lukasiewicz Logic Algebra...
Kronenberg, S; Jordan, T; Bechtel, E; Gentner, F; Groeber, E
2002-01-01
This paper reports the results of experiments that were designed to check the validity of the NOVICE Adjoint Monte Carlo Transport code in predicting emission-electron distributions from irradiated targets. Previous work demonstrated that the code accurately calculated total electron yields from irradiated targets. In this investigation, a gold target was irradiated by X-rays with effective quantum energies of 79, 127, 174, 216, and 250 keV. Spectra of electrons from the target were measured for an incident photon angle of 45 deg., an emission-electron polar angle of 45 deg., azimuthal angles of 0 deg. and 180 deg., and in both the forward and backward directions. NOVICE was used to predict those electron-energy-distributions for the same set of experimental conditions. The agreement in shape of the theoretical and experimental distributions was good, whereas the absolute agreement in amplitude was within about a factor of 2 over most of the energy range of the spectra. Previous experimental and theoretical c...
INL Experimental Program Roadmap for Thermal Hydraulic Code Validation
Energy Technology Data Exchange (ETDEWEB)
Glenn McCreery; Hugh McIlroy
2007-09-01
Advanced computer modeling and simulation tools and protocols will be heavily relied on for a wide variety of system studies, engineering design activities, and other aspects of the Next Generation Nuclear Power (NGNP) Very High Temperature Reactor (VHTR), the DOE Global Nuclear Energy Partnership (GNEP), and light-water reactors. The goal is for all modeling and simulation tools to be demonstrated accurate and reliable through a formal Verification and Validation (V&V) process, especially where such tools are to be used to establish safety margins and support regulatory compliance, or to design a system in a manner that reduces the role of expensive mockups and prototypes. Recent literature identifies specific experimental principles that must be followed in order to insure that experimental data meet the standards required for a “benchmark” database. Even for well conducted experiments, missing experimental details, such as geometrical definition, data reduction procedures, and manufacturing tolerances have led to poor Benchmark calculations. The INL has a long and deep history of research in thermal hydraulics, especially in the 1960s through 1980s when many programs such as LOFT and Semiscle were devoted to light-water reactor safety research, the EBRII fast reactor was in operation, and a strong geothermal energy program was established. The past can serve as a partial guide for reinvigorating thermal hydraulic research at the laboratory. However, new research programs need to fully incorporate modern experimental methods such as measurement techniques using the latest instrumentation, computerized data reduction, and scaling methodology. The path forward for establishing experimental research for code model validation will require benchmark experiments conducted in suitable facilities located at the INL. This document describes thermal hydraulic facility requirements and candidate buildings and presents examples of suitable validation experiments related
Informed consent in human experimentation before the Nuremberg code.
Vollmann, J; Winau, R
1996-12-07
The issue of ethics with respect to medical experimentation in Germany during the 1930s and 1940s was crucial at the Nuremberg trials and related trials of doctors and public health officials. Those involved in horrible crimes attempted to excuse themselves by arguing that there were no explicit rules governing medical research on human beings in Germany during the period and that research practices in Germany were not different from those in allied countries. In this context the Nuremberg code of 1947 is generally regarded as the first document to set out ethical regulations in human experimentation based on informed consent. New research, however, indicates that ethical issues of informed consent in guidelines for human experimentation were recognised as early as the nineteenth century. These guidelines shed light on the still contentious issue of when the concepts of autonomy, informed consent, and therapeutic and non-therapeutic research first emerged. This issue assumes renewed importance in the context of current attempts to assess liability and responsibility for the abuse of people in various experiments conducted since the second world war in the United States, Canada, Russia, and other nations.
Error Correction using Quantum Quasi-Cyclic Low-Density Parity-Check(LDPC) Codes
Jing, Lin; Brun, Todd; Quantum Research Team
Quasi-cyclic LDPC codes can approach the Shannon capacity and have efficient decoders. Manabu Hagiwara et al., 2007 presented a method to calculate parity check matrices with high girth. Two distinct, orthogonal matrices Hc and Hd are used. Using submatrices obtained from Hc and Hd by deleting rows, we can alter the code rate. The submatrix of Hc is used to correct Pauli X errors, and the submatrix of Hd to correct Pauli Z errors. We simulated this system for depolarizing noise on USC's High Performance Computing Cluster, and obtained the block error rate (BER) as a function of the error weight and code rate. From the rates of uncorrectable errors under different error weights we can extrapolate the BER to any small error probability. Our results show that this code family can perform reasonably well even at high code rates, thus considerably reducing the overhead compared to concatenated and surface codes. This makes these codes promising as storage blocks in fault-tolerant quantum computation. Error Correction using Quantum Quasi-Cyclic Low-Density Parity-Check(LDPC) Codes.
Experimental verification of multipartite entanglement in quantum networks
McCutcheon, W.; Pappa, A.; Bell, B. A.; McMillan, A.; Chailloux, A.; Lawson, T.; Mafu, M.; Markham, D.; Diamanti, E.; Kerenidis, I.; Rarity, J. G.; Tame, M. S.
2016-11-01
Multipartite entangled states are a fundamental resource for a wide range of quantum information processing tasks. In particular, in quantum networks, it is essential for the parties involved to be able to verify if entanglement is present before they carry out a given distributed task. Here we design and experimentally demonstrate a protocol that allows any party in a network to check if a source is distributing a genuinely multipartite entangled state, even in the presence of untrusted parties. The protocol remains secure against dishonest behaviour of the source and other parties, including the use of system imperfections to their advantage. We demonstrate the verification protocol in a three- and four-party setting using polarization-entangled photons, highlighting its potential for realistic photonic quantum communication and networking applications.
Experimental bit commitment based on quantum communication and special relativity.
Lunghi, T; Kaniewski, J; Bussières, F; Houlmann, R; Tomamichel, M; Kent, A; Gisin, N; Wehner, S; Zbinden, H
2013-11-01
Bit commitment is a fundamental cryptographic primitive in which Bob wishes to commit a secret bit to Alice. Perfectly secure bit commitment between two mistrustful parties is impossible through asynchronous exchange of quantum information. Perfect security is however possible when Alice and Bob split into several agents exchanging classical and quantum information at times and locations suitably chosen to satisfy specific relativistic constraints. Here we report on an implementation of a bit commitment protocol using quantum communication and special relativity. Our protocol is based on [A. Kent, Phys. Rev. Lett. 109, 130501 (2012)] and has the advantage that it is practically feasible with arbitrary large separations between the agents in order to maximize the commitment time. By positioning agents in Geneva and Singapore, we obtain a commitment time of 15 ms. A security analysis considering experimental imperfections and finite statistics is presented.
Comparing TCV experimental VDE responses with DINA code simulations
Energy Technology Data Exchange (ETDEWEB)
Favez, J.Y.; Khayrutdinov, J.B.; Lister, J.B.; Lukash, V.E
2001-10-01
The DINA free-boundary equilibrium simulation code has been implemented for TCV, including the full TCV feedback and diagnostic systems. First results showed good agreement with control coil perturbations and correctly reproduced certain non-linear features in the experimental measurements. The latest DINA code simulations, presented in this paper, exploit discharges with different cross- sectional shapes and different vertical instability growth rates which were subjected to controlled Vertical Displacement Events, extending previous work with the DINA code on the DIII-D tokamak. The height of the TCV vessel allows observation of the non- linear evolution of the VDE growth rate as regions of different vertical field decay index are crossed. The vertical movement of the plasma is found to be well modelled. For most experiments, DINA reproduces the S-shape of the vertical displacement in TCV with excellent precision. This behaviour cannot be modelled using linear time-independent models because of the predominant exponential shape due to the unstable pole of any linear time-independent model. The other most common equilibrium parameters like the plasma current Ip, the elongation K, the triangularity d, the safety factor q, the ratio between the averaged plasma kinetic pressure and the pressure of the poloidal magnetic field at the edge of the plasma bp and the internal self inductance l also show acceptable agreement. The evolution of the growth rate g is estimated and compared with the evolution of the closed loop growth rate calculated with the RZIP linear model, confirming the origin of the observed behaviour. (author)
Modeling experimental plasma diagnostics in the FLASH code: Thomson scattering
Weide, Klaus; Flocke, Norbert; Feister, Scott; Tzeferacos, Petros; Lamb, Donald
2017-10-01
Spectral analysis of the Thomson scattering of laser light sent into a plasma provides an experimental method to quantify plasma properties in laser-driven plasma experiments. We have implemented such a synthetic Thomson scattering diagnostic unit in the FLASH code, to emulate the probe-laser propagation, scattering and spectral detection. User-defined laser rays propagate into the FLASH simulation region and experience scattering (change in direction and frequency) based on plasma parameters. After scattering, the rays propagate out of the interaction region and are spectrally characterized. The diagnostic unit can be used either during a physics simulation or in post-processing of simulation results. FLASH is publicly available at flash.uchicago.edu. U.S. DOE NNSA, U.S. DOE NNSA ASC, U.S. DOE Office of Science and NSF.
(Submitted) Scalable quantum circuit and control for a superconducting surface code
Versluis, R.; Poletto, S.; Khammassi, N.; Haider, N.; Michalak, D.J.; Bruno, A.; Bertels, K.; DiCarlo, L.
2016-01-01
We present a scalable scheme for executing the error-correction cycle of a monolithic surface-code fabric composed of fast-flux-tuneable transmon qubits with nearest-neighbor coupling. An eight-qubit unit cell forms the basis for repeating both the quantum hardware and coherent control, enabling
Directory of Open Access Journals (Sweden)
Daniel Litinski
2017-09-01
Full Text Available We present a scalable architecture for fault-tolerant topological quantum computation using networks of voltage-controlled Majorana Cooper pair boxes and topological color codes for error correction. Color codes have a set of transversal gates which coincides with the set of topologically protected gates in Majorana-based systems, namely, the Clifford gates. In this way, we establish color codes as providing a natural setting in which advantages offered by topological hardware can be combined with those arising from topological error-correcting software for full-fledged fault-tolerant quantum computing. We provide a complete description of our architecture, including the underlying physical ingredients. We start by showing that in topological superconductor networks, hexagonal cells can be employed to serve as physical qubits for universal quantum computation, and we present protocols for realizing topologically protected Clifford gates. These hexagonal-cell qubits allow for a direct implementation of open-boundary color codes with ancilla-free syndrome read-out and logical T gates via magic-state distillation. For concreteness, we describe how the necessary operations can be implemented using networks of Majorana Cooper pair boxes, and we give a feasibility estimate for error correction in this architecture. Our approach is motivated by nanowire-based networks of topological superconductors, but it could also be realized in alternative settings such as quantum-Hall–superconductor hybrids.
Hybrid threshold adaptable quantum secret sharing scheme with reverse Huffman-Fibonacci-tree coding
Lai, Hong; Zhang, Jun; Luo, Ming-Xing; Pan, Lei; Pieprzyk, Josef; Xiao, Fuyuan; Orgun, Mehmet A.
2016-08-01
With prevalent attacks in communication, sharing a secret between communicating parties is an ongoing challenge. Moreover, it is important to integrate quantum solutions with classical secret sharing schemes with low computational cost for the real world use. This paper proposes a novel hybrid threshold adaptable quantum secret sharing scheme, using an m-bonacci orbital angular momentum (OAM) pump, Lagrange interpolation polynomials, and reverse Huffman-Fibonacci-tree coding. To be exact, we employ entangled states prepared by m-bonacci sequences to detect eavesdropping. Meanwhile, we encode m-bonacci sequences in Lagrange interpolation polynomials to generate the shares of a secret with reverse Huffman-Fibonacci-tree coding. The advantages of the proposed scheme is that it can detect eavesdropping without joint quantum operations, and permits secret sharing for an arbitrary but no less than threshold-value number of classical participants with much lower bandwidth. Also, in comparison with existing quantum secret sharing schemes, it still works when there are dynamic changes, such as the unavailability of some quantum channel, the arrival of new participants and the departure of participants. Finally, we provide security analysis of the new hybrid quantum secret sharing scheme and discuss its useful features for modern applications.
Analysis of a Quantum Error Correcting Code using Quantum Process Calculus
Directory of Open Access Journals (Sweden)
Timothy A. S. Davidson
2012-10-01
Full Text Available We describe the use of quantum process calculus to describe and analyze quantum communication protocols, following the successful field of formal methods from classical computer science. The key idea is to define two systems, one modelling a protocol and one expressing a specification, and prove that they are behaviourally equivalent. We summarize the necessary theory in the process calculus CQP, including the crucial result that equivalence is a congruence, meaning that it is preserved by embedding in any context. We illustrate the approach by analyzing two versions of a quantum error correction system.
Real-Coded Quantum-Inspired Genetic Algorithm-Based BP Neural Network Algorithm
Directory of Open Access Journals (Sweden)
Jianyong Liu
2015-01-01
Full Text Available The method that the real-coded quantum-inspired genetic algorithm (RQGA used to optimize the weights and threshold of BP neural network is proposed to overcome the defect that the gradient descent method makes the algorithm easily fall into local optimal value in the learning process. Quantum genetic algorithm (QGA is with good directional global optimization ability, but the conventional QGA is based on binary coding; the speed of calculation is reduced by the coding and decoding processes. So, RQGA is introduced to explore the search space, and the improved varied learning rate is adopted to train the BP neural network. Simulation test shows that the proposed algorithm is effective to rapidly converge to the solution conformed to constraint conditions.
Provably Secure Experimental Quantum Bit-String Generation
Lamoureux, Louis-Philippe; Brainis, Edouard; Amans, David; Barrett, Jonathan; Massar, Serge
2004-01-01
Coin tossing is a cryptographic task in which two parties who do not trust each other aim to generate a common random bit. Using classical communication this is impossible, but non trivial coin tossing is possible using quantum communication. Here we consider the case when the parties do not want to toss a single coin, but many. This is called bit string generation. We report the experimental generation of strings of coins which are provably more random than achievable using classical communi...
Experimental measurement-device-independent quantum random-number generation
Nie, You-Qi; Guan, Jian-Yu; Zhou, Hongyi; Zhang, Qiang; Ma, Xiongfeng; Zhang, Jun; Pan, Jian-Wei
2016-12-01
The randomness from a quantum random-number generator (QRNG) relies on the accurate characterization of its devices. However, device imperfections and inaccurate characterizations can result in wrong entropy estimation and bias in practice, which highly affects the genuine randomness generation and may even induce the disappearance of quantum randomness in an extreme case. Here we experimentally demonstrate a measurement-device-independent (MDI) QRNG based on time-bin encoding to achieve certified quantum randomness even when the measurement devices are uncharacterized and untrusted. The MDI-QRNG is randomly switched between the regular randomness generation mode and a test mode, in which four quantum states are randomly prepared to perform measurement tomography in real time. With a clock rate of 25 MHz, the MDI-QRNG generates a final random bit rate of 5.7 kbps. Such implementation with an all-fiber setup provides an approach to construct a fully integrated MDI-QRNG with trusted but error-prone devices in practice.
Quantum Hall effects recent theoretical and experimental developments
Ezawa, Zyun Francis
2013-01-01
Enthusiasm for research on the quantum Hall effect (QHE) is unbounded. The QHE is one of the most fascinating and beautiful phenomena in all branches of physics. Tremendous theoretical and experimental developments are still being made in this sphere. Composite bosons, composite fermions and anyons were among distinguishing ideas in the original edition. In the 2nd edition, fantastic phenomena associated with the interlayer phase coherence in the bilayer system were extensively described. The microscopic theory of the QHE was formulated based on the noncommutative geometry. Furthermore, the unconventional QHE in graphene was reviewed, where the electron dynamics can be treated as relativistic Dirac fermions and even the supersymmetric quantum mechanics plays a key role. In this 3rd edition, all chapters are carefully reexamined and updated. A highlight is the new chapter on topological insulators. Indeed, the concept of topological insulator stems from the QHE. Other new topics are recent prominent experime...
Percolation bounds for decoding thresholds with correlated erasures in quantum LDPC codes
Hamilton, Kathleen; Pryadko, Leonid
Correlations between errors can dramatically affect decoding thresholds, in some cases eliminating the threshold altogether. We analyze the existence of a threshold for quantum low-density parity-check (LDPC) codes in the case of correlated erasures. When erasures are positively correlated, the corresponding multi-variate Bernoulli distribution can be modeled in terms of cluster errors, where qubits in clusters of various size can be marked all at once. In a code family with distance scaling as a power law of the code length, erasures can be always corrected below percolation on a qubit adjacency graph associated with the code. We bound this correlated percolation transition by weighted (uncorrelated) percolation on a specially constructed cluster connectivity graph, and apply our recent results to construct several bounds for the latter. This research was supported in part by the NSF Grant PHY-1416578 and by the ARO Grant W911NF-14-1-0272.
Experimental Minimum-Error Quantum-State Discrimination in High Dimensions.
Solís-Prosser, M A; Fernandes, M F; Jiménez, O; Delgado, A; Neves, L
2017-03-10
Quantum mechanics forbids perfect discrimination among nonorthogonal states through a single shot measurement. To optimize this task, many strategies were devised that later became fundamental tools for quantum information processing. Here, we address the pioneering minimum-error (ME) measurement and give the first experimental demonstration of its application for discriminating nonorthogonal states in high dimensions. Our scheme is designed to distinguish symmetric pure states encoded in the transverse spatial modes of an optical field; the optimal measurement is performed by a projection onto the Fourier transform basis of these modes. For dimensions ranging from D=2 to D=21 and nearly 14 000 states tested, the deviations of the experimental results from the theoretical values range from 0.3% to 3.6% (getting below 2% for the vast majority), thus showing the excellent performance of our scheme. This ME measurement is a building block for high-dimensional implementations of many quantum communication protocols, including probabilistic state discrimination, dense coding with nonmaximal entanglement, and cryptographic schemes.
Quantum-Enhanced Cyber Security: Experimental Computation on Quantum-Encrypted Data
2017-03-02
of using polarization qubits on a chip is coupling the photons from free space spontaneous parametric down- conversion sources to the chip...respect to regular quantum computer architectures , creating processes without a causal order is an experimental task. Supported by this project we...definite causal order by measuring a causal witness. This mathematical object incorporates a series of measurements which are designed to yield a
Experimental Minimum-Error Quantum-State Discrimination in High Dimensions
Solís-Prosser, M. A.; Fernandes, M. F.; Jiménez, O.; Delgado, A.; Neves, L.
2017-03-01
Quantum mechanics forbids perfect discrimination among nonorthogonal states through a single shot measurement. To optimize this task, many strategies were devised that later became fundamental tools for quantum information processing. Here, we address the pioneering minimum-error (ME) measurement and give the first experimental demonstration of its application for discriminating nonorthogonal states in high dimensions. Our scheme is designed to distinguish symmetric pure states encoded in the transverse spatial modes of an optical field; the optimal measurement is performed by a projection onto the Fourier transform basis of these modes. For dimensions ranging from D =2 to D =21 and nearly 14 000 states tested, the deviations of the experimental results from the theoretical values range from 0.3% to 3.6% (getting below 2% for the vast majority), thus showing the excellent performance of our scheme. This ME measurement is a building block for high-dimensional implementations of many quantum communication protocols, including probabilistic state discrimination, dense coding with nonmaximal entanglement, and cryptographic schemes.
A New Quantum Key Distribution Scheme based on Frequency and Time Coding
Zhu, Chang-hua; Pei, Chang-xing; Quan, Dong-xiao; Chen, Nan; Yi, Yun-hui
2010-01-01
A new scheme of quantum key distribution (QKD) using frequency and time coding is proposed, in which the security is based on the frequency-time uncertainty relation. In this scheme, the binary information sequence is encoded randomly on either the central frequency or the time delay at the sender. The central frequency of the single photon pulse is set as omega1 for bit "0" and set as omega2 for bit "1" when frequency coding is selected. While, the single photon pulse is not delayed for bit ...
Experimentally freezing quantum discord in a dephasing environment using dynamical decoupling
Singh, Harpreet; Arvind; Dorai, Kavita
2017-06-01
The discovery of the intriguing phenomenon that certain kinds of quantum correlations remain impervious to noise up to a specific point in time and then suddenly decay, has generated immense recent interest. We exploit dynamical decoupling sequences to prolong the persistence of time-invariant quantum correlations in a system of two NMR qubits decohering in independent dephasing environments. We experimentally prepare two-qubit Bell-diagonal quantum states that interact with individual noise channels and demonstrate that we are able to freeze quantum correlations over long time scales via dynamical decoupling. Our results have important implications for experimental quantum control and for quantum information processing protocols.
Quantum Phase Transitions of the Majorana Toric Code in the Presence of Finite Cooper-Pair Tunneling
Roy, Ananda; Terhal, Barbara M.; Hassler, Fabian
2017-11-01
The toric code based on Majorana fermions on mesoscopic superconducting islands is a promising candidate for quantum information processing. In the limit of vanishing Cooper-pair tunneling, it has been argued that the phase transition separating the topologically ordered phase of the toric code from the trivial one is in the universality class of the (2 +1 )D X Y model. On the other hand, in the limit of infinitely large Cooper-pair tunneling, the phase transition is in the universality class of the (2 +1 )D Ising model. In this work, we treat the case of finite Cooper-pair tunneling and address the question of how the continuous X Y symmetry breaking phase transition turns into a discrete Z2 symmetry breaking one when the Cooper-pair tunneling rate is increased. We show that this happens through a couple of tricritical points and first order phase transitions. Using a Jordan-Wigner transformation, we map the problem to that of spins coupled to quantum rotors and subsequently, propose a Landau field theory for this model that matches the known results in the respective limits. We calculate the effective field theories and provide the relevant critical exponents for the different phase transitions. Our results are relevant for predicting the stability of the topological phase in realistic experimental implementations.
Experimental Aspects of Code Validation in Hypersonic Flows
Chanetz, Bruno; Délery, Jean
2005-05-01
In spite of the spectacular progress in CFD there is still a strong need to validate the computer codes by comparison with experiments. The first validation step is the assessment of the code numerical safety and the physical models accuracy. This validation step requires carefully made building block experiments. To be calculable, such experiments must satisfy conditions such as the precise definition of the test set-up geometry, the absence of uncontrolled parasitic effects, a complete information on the flow conditions and indication on the uncertainty margins. Under these conditions, the experiment can be put into a data bank which will be precious to help in the development of reliable and accurate codes. The paper provides an overview of modern measurement techniques for hypersonic flows analysis. The demonstration is illustrated by laminar experiments used to assess the numerical accuracy of codes run in high Mach number flows.
Algorithms and computer codes for atomic and molecular quantum scattering theory. Volume I
Energy Technology Data Exchange (ETDEWEB)
Thomas, L. (ed.)
1979-01-01
The goals of this workshop are to identify which of the existing computer codes for solving the coupled equations of quantum molecular scattering theory perform most efficiently on a variety of test problems, and to make tested versions of those codes available to the chemistry community through the NRCC software library. To this end, many of the most active developers and users of these codes have been invited to discuss the methods and to solve a set of test problems using the LBL computers. The first volume of this workshop report is a collection of the manuscripts of the talks that were presented at the first meeting held at the Argonne National Laboratory, Argonne, Illinois June 25-27, 1979. It is hoped that this will serve as an up-to-date reference to the most popular methods with their latest refinements and implementations.
Comparison of GLIMPS and HFAST Stirling engine code predictions with experimental data
Geng, Steven M.; Tew, Roy C.
1992-01-01
Predictions from GLIMPS and HFAST design codes are compared with experimental data for the RE-1000 and SPRE free piston Stirling engines. Engine performance and available power loss predictions are compared. Differences exist between GLIMPS and HFAST loss predictions. Both codes require engine specific calibration to bring predictions and experimental data into agreement.
Position-based coding and convex splitting for private communication over quantum channels
Wilde, Mark M.
2017-10-01
The classical-input quantum-output (cq) wiretap channel is a communication model involving a classical sender X, a legitimate quantum receiver B, and a quantum eavesdropper E. The goal of a private communication protocol that uses such a channel is for the sender X to transmit a message in such a way that the legitimate receiver B can decode it reliably, while the eavesdropper E learns essentially nothing about which message was transmitted. The ɛ -one-shot private capacity of a cq wiretap channel is equal to the maximum number of bits that can be transmitted over the channel, such that the privacy error is no larger than ɛ \\in (0,1). The present paper provides a lower bound on the ɛ -one-shot private classical capacity, by exploiting the recently developed techniques of Anshu, Devabathini, Jain, and Warsi, called position-based coding and convex splitting. The lower bound is equal to a difference of the hypothesis testing mutual information between X and B and the "alternate" smooth max-information between X and E. The one-shot lower bound then leads to a non-trivial lower bound on the second-order coding rate for private classical communication over a memoryless cq wiretap channel.
DEFF Research Database (Denmark)
Abdali, Salim; Jensen, Morten Østergaard; Bohr, Henrik
2003-01-01
This paper describes a theoretical and experimental study of [Leu]enkephalin conformations with respect to the quantum estates of the atomic structure of the peptide. Results from vibrational absorption measurements and quantum calculations are used to outline a quantum picture and to assign vibr...
Directory of Open Access Journals (Sweden)
Jian Li
2015-09-01
Full Text Available A novel quantum secure direct communication protocol based on four-particle genuine entangled state and quantum dense coding is proposed. In this protocol, the four-particle genuine entangled state is used to detect eavesdroppers, and quantum dense coding is used to encode the message. Finally, the security of the proposed protocol is discussed. During the security analysis, the method of entropy theory is introduced, and two detection strategies are compared quantitatively by comparing the relationship between the maximal information that the eavesdroppers (Eve can obtain, and the probability of being detected. Through the analysis we can state that our scheme is feasible and secure.
Xu, Kebiao; Xie, Tianyu; Li, Zhaokai; Xu, Xiangkun; Wang, Mengqi; Ye, Xiangyu; Kong, Fei; Geng, Jianpei; Duan, Changkui; Shi, Fazhan; Du, Jiangfeng
2017-03-31
The adiabatic quantum computation is a universal and robust method of quantum computing. In this architecture, the problem can be solved by adiabatically evolving the quantum processor from the ground state of a simple initial Hamiltonian to that of a final one, which encodes the solution of the problem. Adiabatic quantum computation has been proved to be a compatible candidate for scalable quantum computation. In this Letter, we report on the experimental realization of an adiabatic quantum algorithm on a single solid spin system under ambient conditions. All elements of adiabatic quantum computation, including initial state preparation, adiabatic evolution (simulated by optimal control), and final state read-out, are realized experimentally. As an example, we found the ground state of the problem Hamiltonian S_{z}I_{z} on our adiabatic quantum processor, which can be mapped to the factorization of 35 into its prime factors 5 and 7.
High performance reconciliation for continuous-variable quantum key distribution with LDPC code
Lin, Dakai; Huang, Duan; Huang, Peng; Peng, Jinye; Zeng, Guihua
2015-03-01
Reconciliation is a significant procedure in a continuous-variable quantum key distribution (CV-QKD) system. It is employed to extract secure secret key from the resulted string through quantum channel between two users. However, the efficiency and the speed of previous reconciliation algorithms are low. These problems limit the secure communication distance and the secure key rate of CV-QKD systems. In this paper, we proposed a high-speed reconciliation algorithm through employing a well-structured decoding scheme based on low density parity-check (LDPC) code. The complexity of the proposed algorithm is reduced obviously. By using a graphics processing unit (GPU) device, our method may reach a reconciliation speed of 25 Mb/s for a CV-QKD system, which is currently the highest level and paves the way to high-speed CV-QKD.
Experimental Demonstration of Quantum Imaging by Coherent Enhancement
McConnell, Robert; Bruzewicz, Colin; Low, Guang Hao; Yoder, Theodore; Chiaverini, John; Sage, Jeremy; Chuang, Isaac
2016-05-01
Classical (incoherent) imaging requires scattering many photons from a target to be imaged and provides resolution which improves statistically with the square root of the number of scattered photons, and hence with the square root of interrogation time. In contrast, quantum imaging by coherent enhancement utilizes coherent excitation of the target to provide imaging resolution which improves linearly with time, achieving the Heisenberg limit for scaling. We present experimental progress towards the realization of quantum-enhanced imaging in a trapped-ion system. A narrow-linewidth laser drives a long-coherence-time transition in a confined 88 Sr+ ion; precise phase control over the excitation sequence allows an optimally narrow and unambiguous excitation of the ion as a function of laser intensity which results in very precise localization of the target within the profile of the addressing beam. This technique may have applications in radar imaging, where long-wavelength radiation is used to penetrate clouds or other obstructions but where large diffraction-limited spot size ordinarily limits resolution.
Experimental Realization of a Compressed Quantum Simulation of a 32-Spin Ising Chain
Li, Zhaokai; Zhou, Hui; Ju, Chenyong; Chen, Hongwei; Zheng, Wenqiang; Lu, Dawei; Rong, Xing; Duan, Changkui; Peng, Xinhua; Du, Jiangfeng
2014-06-01
Certain n-qubit quantum systems can be faithfully simulated by quantum circuits with only O(log(n)) qubits [B. Kraus, Phys. Rev. Lett. 107, 250503 (2011)]. Here we report an experimental realization of this compressed quantum simulation on a one-dimensional Ising chain. By utilizing an nuclear magnetic resonance quantum simulator with only five qubits, the property of ground-state magnetization of an open-boundary 32-spin Ising model is experimentally simulated, prefacing the expected quantum phase transition in the thermodynamic limit. This experimental protocol can be straightforwardly extended to systems with hundreds of spins by compressing them into up to merely 10-qubit systems. Our experiment paves the way for exploring physical phenomena in large-scale quantum systems with quantum simulators under current technology.
Experimental adaptive quantum tomography of two-qubit states
Struchalin, G. I.; Pogorelov, I. A.; Straupe, S. S.; Kravtsov, K. S.; Radchenko, I. V.; Kulik, S. P.
2016-01-01
We report an experimental realization of adaptive Bayesian quantum state tomography for two-qubit states. Our implementation is based on the adaptive experimental design strategy proposed in the work by Huszár and Houlsby [F. Huszár and N. M. T. Houlsby, Phys. Rev. A 85, 052120 (2012)., 10.1103/PhysRevA.85.052120] and provides an optimal measurement approach in terms of the information gain. We address the practical questions which one faces in any experimental application: the influence of technical noise and the behavior of the tomographic algorithm for an easy-to-implement class of factorized measurements. In an experiment with polarization states of entangled photon pairs, we observe a lower instrumental noise floor and superior reconstruction accuracy for nearly pure states of the adaptive protocol compared to a nonadaptive protocol. At the same time, we show that for the mixed states, the restriction to factorized measurements results in no advantage for adaptive measurements, so general measurements have to be used.
Fortran code for generating random probability vectors, unitaries, and quantum states
Directory of Open Access Journals (Sweden)
Jonas eMaziero
2016-03-01
Full Text Available The usefulness of generating random configurations is recognized in many areas of knowledge. Fortran was born for scientific computing and has been one of the main programming languages in this area since then. And several ongoing projects targeting towards its betterment indicate that it will keep this status in the decades to come. In this article, we describe Fortran codes produced, or organized, for the generation of the following random objects: numbers, probability vectors, unitary matrices, and quantum state vectors and density matrices. Some matrix functions are also included and may be of independent interest.
Directory of Open Access Journals (Sweden)
Duc Manh Nguyen
2017-07-01
Full Text Available In this paper, new construction methods of entanglement-assisted quantum error correction code (EAQECC from circulant matrices are proposed. We first construct the matrices from two vectors of constraint size, and determine the isotropic subgroup. Then, we also propose a method for calculation of the entanglement subgroup based on standard forms of binary matrices to satisfy the constraint conditions of EAQECC. With isotropic and entanglement subgroups, we determine all the parameters and the minimum distance of the EAQECC. The proposed EAQECC with small lengths are presented to explain the practicality of this construction of EAQECC. Comparison with some earlier constructions of EAQECC shows that the proposed EAQECC is better.
Magic-State Distillation in All Prime Dimensions Using Quantum Reed-Muller Codes
Directory of Open Access Journals (Sweden)
Earl T. Campbell
2012-12-01
Full Text Available We propose families of protocols for magic-state distillation—important components of fault-tolerance schemes—for systems of odd prime dimension. Our protocols utilize quantum Reed-Muller codes with transversal non-Clifford gates. We find that, in higher dimensions, small and effective codes can be used that have no direct analogue in qubit (two-dimensional systems. We present several concrete protocols, including schemes for three-dimensional (qutrit and five-dimensional (ququint systems. The five-dimensional protocol is, by many measures, the best magic-state-distillation scheme yet discovered. It excels both in terms of error threshold with respect to depolarizing noise (36.3% and the efficiency measure known as yield, where, for a large region of parameters, it outperforms its qubit counterpart by many orders of magnitude.
Experimental quantum Zeno effect in NMR with entanglement-based measurement
Zheng, Wenqiang; Xu, D. Z.; Peng, Xinhua; Zhou, Xianyi; Du, Jiangfeng; Sun, C. P.
2013-01-01
We experimentally demonstrate a new dynamic fashion of quantum Zeno effect in nuclear magnetic resonance systems. The frequent measurements are implemented through quantum entanglement between the target qubit(s) and the measuring qubit, which dynamically results from the unitary evolution of duration $\\tau_{m}$ due to dispersive-coupling. Experimental results testify the presence of "the critical measurement time effect", that is, the quantum Zeno effect does not occur when $\\tau_{m}$ takes ...
Zhang, Wei; Ding, Dong-Sheng; Dong, Ming-Xin; Shi, Shuai; Wang, Kai; Liu, Shi-Long; Li, Yan; Zhou, Zhi-Yuan; Shi, Bao-Sen; Guo, Guang-Can
2016-11-14
Entanglement in multiple degrees of freedom has many benefits over entanglement in a single one. The former enables quantum communication with higher channel capacity and more efficient quantum information processing and is compatible with diverse quantum networks. Establishing multi-degree-of-freedom entangled memories is not only vital for high-capacity quantum communication and computing, but also promising for enhanced violations of nonlocality in quantum systems. However, there have been yet no reports of the experimental realization of multi-degree-of-freedom entangled memories. Here we experimentally established hyper- and hybrid entanglement in multiple degrees of freedom, including path (K-vector) and orbital angular momentum, between two separated atomic ensembles by using quantum storage. The results are promising for achieving quantum communication and computing with many degrees of freedom.
Annular tautomerism: experimental observations and quantum mechanics calculations
Cruz-Cabeza, Aurora J.; Schreyer, Adrian; Pitt, William R.
2010-06-01
The use of MP2 level quantum mechanical (QM) calculations on isolated heteroaromatic ring systems for the prediction of the tautomeric propensities of whole molecules in a crystalline environment was examined. A Polarisable Continuum Model was used in the calculations to account for environment effects on the tautomeric relative stabilities. The calculated relative energies of tautomers were compared to relative abundances within the Cambridge Structural Database (CSD) and the Protein Data Bank (PDB). The work was focussed on 84 annular tautomeric forms of 34 common ring systems. Good agreement was found between the calculations and the experimental data even if the quantity of these data was limited in many cases. The QM results were compared to those produced by much faster semiempirical calculations. In a search for other sources of the useful experimental data, the relative numbers of known compounds in which prototropic positions were often substituted by heavy atoms were also analysed. A scheme which groups all annular tautomeric transformations into 10 classes was developed. The scheme was designed to encompass a comprehensive set of known and theoretically possible tautomeric ring systems generated as part of a previous study. General trends across analogous ring systems were detected as a result. The calculations and statistics collected on crystallographic data as well as the general trends observed should be useful for the better modelling of annular tautomerism in the applications such as computer-aided drug design, small molecule crystal structure prediction, the naming of compounds and the interpretation of protein—small molecule crystal structures.
Experimental magic state distillation for fault-tolerant quantum computing.
Souza, Alexandre M; Zhang, Jingfu; Ryan, Colm A; Laflamme, Raymond
2011-01-25
Any physical quantum device for quantum information processing (QIP) is subject to errors in implementation. In order to be reliable and efficient, quantum computers will need error-correcting or error-avoiding methods. Fault-tolerance achieved through quantum error correction will be an integral part of quantum computers. Of the many methods that have been discovered to implement it, a highly successful approach has been to use transversal gates and specific initial states. A critical element for its implementation is the availability of high-fidelity initial states, such as |0〉 and the 'magic state'. Here, we report an experiment, performed in a nuclear magnetic resonance (NMR) quantum processor, showing sufficient quantum control to improve the fidelity of imperfect initial magic states by distilling five of them into one with higher fidelity.
Quantum codes from cyclic codes over F3 + μF3 + υF3 + μυ F3
Özen, Mehmet; Tuğba Özzaim, N.; İnce, Halit
2016-10-01
In this paper, it will be argued that structure of cyclic codes over F3 + μF3 + υF3 + μυ F3 where u 2 = 1, v 2 = 1 and uv = vu for arbitrary length n. We define a new Gray map which is a distance preserving map. By using decomposition theory, we find generator polynomials of cyclic codes over F3 + μF3 + υF3 + μυ F3 and obtain the result that cyclic codes over F3 + μF3 + υF3 + μυ F3 are principally generated. Further, using these results we determine the parameters of quantum codes which constructed from cyclic codes over F3 + μF3 + υF3 + μυ F3. We present some of the results of computer search.
Hagar, Amit
Among the alternatives of non-relativistic quantum mechanics (NRQM) there are those that give different predictions than quantum mechanics in yet-untested circumstances, while remaining compatible with current empirical findings. In order to test these predictions, one must isolate one's system from environmental induced decoherence, which, on the standard view of NRQM, is the dynamical mechanism that is responsible for the 'apparent' collapse in open quantum systems. But while recent advances in condensed-matter physics may lead in the near future to experimental setups that will allow one to test the two hypotheses, namely genuine collapse vs. decoherence, hence make progress toward a solution to the quantum measurement problem, those philosophers and physicists who are advocating an information-theoretic approach to the foundations of quantum mechanics are still unwilling to acknowledge the empirical character of the issue at stake. Here I argue that in doing so they are displaying an unwarranted double standard.
Computational and Experimental Methods to Decipher the Epigenetic Code
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Stefano ede Pretis
2014-09-01
Full Text Available A multi-layered set of epigenetic marks, including post-translational modifications of histones and methylation of DNA, is finely tuned to define the epigenetic state of chromatin in any given cell type under specific conditions. Recently, the knowledge about the combinations of epigenetic marks occurring in the genome of different cell types under various conditions is rapidly increasing. Computational methods were developed for the identification of these states, unraveling the combinatorial nature of epigenetic marks and their association to genomic functional elements and transcriptional states. Nevertheless, the precise rules defining the interplay between all these marks remain poorly characterized. In this perspective we review the current state of this research field, illustrating the power and the limitations of current approaches. Finally, we sketch future avenues of research illustrating how the adoption of specific experimental designs coupled with available experimental approaches could be critical for a significant progress in this area.
Controlling Quantum Information
Landahl, A J
2002-01-01
Quantum information science explores ways in which quantum physical laws can be harnessed to control the acquisition, transmission, protection, and processing of information. This field has seen explosive growth in the past several years from progress on both theoretical and experimental fronts. Essential to this endeavor are methods for controlling quantum information. In this thesis, I present three new approaches for controlling quantum information. First, I present a new protocol for continuously protecting unknown quantum states from noise. This protocol combines and expands ideas from the theories of quantum error correction and quantum feedback control. The result can outperform either approach by itself. I generalize this protocol to all known quantum stabilizer codes, and study its application to the three-qubit repetition code in detail via Monte Carlo simulations. Next, I present several new protocols for controlling quantum information that are fault-tolerant. These protocols require only local qu...
Experimental nested purification for a linear optical quantum repeater
Chen, Luo-Kan; Yong, Hai-Lin; Xu, Ping; Yao, Xing-Can; Xiang, Tong; Li, Zheng-Da; Liu, Chang; Lu, He; Liu, Nai-Le; Li, Li; Yang, Tao; Peng, Cheng-Zhi; Zhao, Bo; Chen, Yu-Ao; Pan, Jian-Wei
2017-11-01
Quantum repeaters1-4 are essential elements for demonstrating global-scale quantum communication. Over the past few decades, tremendous efforts have been dedicated to implementing a practical quantum repeater5-10. However, nested purification1, the backbone of a quantum repeater, remains a challenge because the capacity for successive entanglement manipulation is still absent. Here, we propose and demonstrate an architecture of nested purification using spontaneous parametric downconversion sources11. A heralded entangled photon pair with higher fidelity is successfully purified from two copies of low-fidelity pairs that experience entanglement swapping and noisy channels. By delicately designing the optical circuits, double-pair emission noise is eliminated automatically and the purified state can be used for scalable entanglement connections to extend the communication distance. Combined with a quantum memory, our approach can be applied immediately in the implemention of a practical quantum repeater.
Experimental demonstration of quantum leader election in linear optics
Okubo, Yuta; Wang, Xiang-Bin; Jiang, Yun-Kun; Tani, Seiichiro; Tomita, Akihisa
2007-01-01
Linear optics is a promising candidate to enable the construction of quantum computers. A number of quantum protocols gates based on linear optics have been demonstrated. However, it is well-known that these gates are non-deterministic and that higher order nonlinearity is necessary for deterministic operations. We found the quantum leader election protocol (QLE) can be operated deterministically only with linear optics, and we have demonstrated the nearly deterministic operation which overco...
Entanglement and Quantum non-locality: an experimental perspective
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Avella Alessio
2013-09-01
Full Text Available The theory of Quantum Mechanics is one of the mainstay of modern physics, a well-established mathematical clockwork whose strength and accuracy in predictions are currently experienced in worldwide research laboratories. As a matter of fact, Quantum Mechanics laid the groundwork of a rich variety of studies ranging from solid state physics to cosmology, from bio-physics to particle physics. The up-to-date ability of manipulating single quantum states is paving the way for emergent quantum technologies as quantum information and computation, quantum communication, quantum metrology and quantum imaging. In spite of the impressive matemathical capacity, a long-standing debate is even revolving around the foundational axioms of this theory, the main bones of content being the non-local effects of entangled states, the wave function collapse and the concept of measurement in Quantum Mechanics, the macro-objectivation problem (the transition from a microscopic probabilistic world to a macroscopic deterministic world described by classical mechanics. Problems that, beyond their fundamental interest in basic science, now also concern the impact of these developing technologies. Without claiming to be complete, this article provides in outline the living matter concerning some of these problems, the implications of which extend deeply on the connection between entanglement and space-time structure.
Experimental Blind Quantum Computing for a Classical Client.
Huang, He-Liang; Zhao, Qi; Ma, Xiongfeng; Liu, Chang; Su, Zu-En; Wang, Xi-Lin; Li, Li; Liu, Nai-Le; Sanders, Barry C; Lu, Chao-Yang; Pan, Jian-Wei
2017-08-04
To date, blind quantum computing demonstrations require clients to have weak quantum devices. Here we implement a proof-of-principle experiment for completely classical clients. Via classically interacting with two quantum servers that share entanglement, the client accomplishes the task of having the number 15 factorized by servers who are denied information about the computation itself. This concealment is accompanied by a verification protocol that tests servers' honesty and correctness. Our demonstration shows the feasibility of completely classical clients and thus is a key milestone towards secure cloud quantum computing.
Experimental Blind Quantum Computing for a Classical Client
Huang, He-Liang; Zhao, Qi; Ma, Xiongfeng; Liu, Chang; Su, Zu-En; Wang, Xi-Lin; Li, Li; Liu, Nai-Le; Sanders, Barry C.; Lu, Chao-Yang; Pan, Jian-Wei
2017-08-01
To date, blind quantum computing demonstrations require clients to have weak quantum devices. Here we implement a proof-of-principle experiment for completely classical clients. Via classically interacting with two quantum servers that share entanglement, the client accomplishes the task of having the number 15 factorized by servers who are denied information about the computation itself. This concealment is accompanied by a verification protocol that tests servers' honesty and correctness. Our demonstration shows the feasibility of completely classical clients and thus is a key milestone towards secure cloud quantum computing.
Pu, Y-F; Jiang, N.; Chang, W.; Yang, H-X; Li, C.; Duan, L-M
2017-01-01
To realize long-distance quantum communication and quantum network, it is required to have multiplexed quantum memory with many memory cells. Each memory cell needs to be individually addressable and independently accessible. Here we report an experiment that realizes a multiplexed DLCZ-type quantum memory with 225 individually accessible memory cells in a macroscopic atomic ensemble. As a key element for quantum repeaters, we demonstrate that entanglement with flying optical qubits can be stored into any neighboring memory cells and read out after a programmable time with high fidelity. Experimental realization of a multiplexed quantum memory with many individually accessible memory cells and programmable control of its addressing and readout makes an important step for its application in quantum information technology. PMID:28480891
Pu, Y.-F.; Jiang, N.; Chang, W.; Yang, H.-X.; Li, C.; Duan, L.-M.
2017-05-01
To realize long-distance quantum communication and quantum network, it is required to have multiplexed quantum memory with many memory cells. Each memory cell needs to be individually addressable and independently accessible. Here we report an experiment that realizes a multiplexed DLCZ-type quantum memory with 225 individually accessible memory cells in a macroscopic atomic ensemble. As a key element for quantum repeaters, we demonstrate that entanglement with flying optical qubits can be stored into any neighboring memory cells and read out after a programmable time with high fidelity. Experimental realization of a multiplexed quantum memory with many individually accessible memory cells and programmable control of its addressing and readout makes an important step for its application in quantum information technology.
Batalhão, Tiago B; Souza, Alexandre M; Mazzola, Laura; Auccaise, Ruben; Sarthour, Roberto S; Oliveira, Ivan S; Goold, John; De Chiara, Gabriele; Paternostro, Mauro; Serra, Roberto M
2014-10-03
We report the experimental reconstruction of the nonequilibrium work probability distribution in a closed quantum system, and the study of the corresponding quantum fluctuation relations. The experiment uses a liquid-state nuclear magnetic resonance platform that offers full control on the preparation and dynamics of the system. Our endeavors enable the characterization of the out-of-equilibrium dynamics of a quantum spin from a finite-time thermodynamics viewpoint.
Experimental bath engineering for quantitative studies of quantum control
CSIR Research Space (South Africa)
Soare, A
2014-04-01
Full Text Available We develop and demonstrate a technique to engineer universal unitary baths in quantum systems. Using the correspondence between unitary decoherence due to ambient environmental noise and errors in a control system for quantum bits, we show how a...
Development of a thermal-hydraulic code for reflood analysis in a PWR experimental loop
Energy Technology Data Exchange (ETDEWEB)
Alves, Sabrina P.; Mesquita, Amir Z.; Rezende, Hugo C., E-mail: sabrinapral@gmail.com, E-mail: amir@cdtn.brm, E-mail: hcr@cdtn.br, E-mail: hcr@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Palma, Daniel A.P., E-mail: dapalma@cnen.gov.br [Comissão Nacional de Energia Nuclear (CNEN), Rio de Janeiro, RJ (Brazil)
2017-07-01
A process of fundamental importance in the event of Loss of Coolant Accident (LOCA) in Pressurized Water nuclear Reactors (PWR) is the reflood of the core or rewetting of nuclear fuels. The Nuclear Technology Development Center (CDTN) has been developing since the 70’s programs to allow Brazil to become independent in the field of reactor safety analysis. To that end, in the 80’s was designed, assembled and commissioned one Rewetting Test Facility (ITR in Portuguese). This facility aims to investigate the phenomena involved in the thermal hydraulic reflood phase of a Loss of Coolant Accident in a PWR nuclear reactor. This work aim is the analysis of physical and mathematical models governing the rewetting phenomenon, and the development a thermo-hydraulic simulation code of a representative experimental circuit of the PWR reactors core cooling channels. It was possible to elaborate and develop a code called REWET. The results obtained with REWET were compared with the experimental results of the ITR, and with the results of the Hydroflut code, that was the old program previously used. An analysis was made of the evolution of the wall temperature of the test section as well as the evolution of the front for two typical tests using the two codes calculation, and experimental results. The result simulated by REWET code for the rewetting time also came closer to the experimental results more than those calculated by Hydroflut code. (author)
Experimental Study of Optimal Measurements for Quantum State Tomography
Sosa-Martinez, H.; Lysne, N. K.; Baldwin, C. H.; Kalev, A.; Deutsch, I. H.; Jessen, P. S.
2017-10-01
Quantum tomography is a critically important tool to evaluate quantum hardware, making it essential to develop optimized measurement strategies that are both accurate and efficient. We compare a variety of strategies using nearly pure test states. Those that are informationally complete for all states are found to be accurate and reliable even in the presence of errors in the measurements themselves, while those designed to be complete only for pure states are far more efficient but highly sensitive to such errors. Our results highlight the unavoidable trade-offs inherent in quantum tomography.
Directory of Open Access Journals (Sweden)
Steven J. Schrodi
2017-01-01
Full Text Available Diagnostic codes within electronic health record systems can vary widely in accuracy. It has been noted that the number of instances of a particular diagnostic code monotonically increases with the accuracy of disease phenotype classification. As a growing number of health system databases become linked with genomic data, it is critically important to understand the effect of this misclassification on the power of genetic association studies. Here, I investigate the impact of this diagnostic code misclassification on the power of genetic association studies with the aim to better inform experimental designs using health informatics data. The trade-off between (i reduced misclassification rates from utilizing additional instances of a diagnostic code per individual and (ii the resulting smaller sample size is explored, and general rules are presented to improve experimental designs.
Zhou, Zong-Quan; Huelga, Susana F; Li, Chuan-Feng; Guo, Guang-Can
2015-09-11
We discuss the use of inequalities of the Leggett-Garg type (LGtI) to witness quantum coherence and present the first experimental violation of this type of inequalities using a light-matter interfaced system. By separately benchmarking the Markovian character of the evolution and the translational invariance of the conditional probabilities, the observed violation of a LGtI is attributed to the quantum coherent character of the process. These results provide a general method to benchmark "quantumness" when the absence of memory effects can be independently certified and confirm the persistence of quantum coherent features within systems of increasing complexity.
Jiang, Xue-Qin; Huang, Peng; Huang, Duan; Lin, Dakai; Zeng, Guihua
2017-02-01
Achieving information theoretic security with practical complexity is of great interest to continuous-variable quantum key distribution in the postprocessing procedure. In this paper, we propose a reconciliation scheme based on the punctured low-density parity-check (LDPC) codes. Compared to the well-known multidimensional reconciliation scheme, the present scheme has lower time complexity. Especially when the chosen punctured LDPC code achieves the Shannon capacity, the proposed reconciliation scheme can remove the information that has been leaked to an eavesdropper in the quantum transmission phase. Therefore, there is no information leaked to the eavesdropper after the reconciliation stage. This indicates that the privacy amplification algorithm of the postprocessing procedure is no more needed after the reconciliation process. These features lead to a higher secret key rate, optimal performance, and availability for the involved quantum key distribution scheme.
Experimental realization of Shor's quantum factoring algorithm using qubit recycling
Martín-López, Enrique; Laing, Anthony; Lawson, Thomas; Alvarez, Roberto; Zhou, Xiao-Qi; O'Brien, Jeremy L.
2012-11-01
Quantum computational algorithms exploit quantum mechanics to solve problems exponentially faster than the best classical algorithms. Shor's quantum algorithm for fast number factoring is a key example and the prime motivator in the international effort to realize a quantum computer. However, due to the substantial resource requirement, to date there have been only four small-scale demonstrations. Here, we address this resource demand and demonstrate a scalable version of Shor's algorithm in which the n-qubit control register is replaced by a single qubit that is recycled n times: the total number of qubits is one-third of that required in the standard protocol. Encoding the work register in higher-dimensional states, we implement a two-photon compiled algorithm to factor N = 21. The algorithmic output is distinguishable from noise, in contrast to previous demonstrations. These results point to larger-scale implementations of Shor's algorithm by harnessing scalable resource reductions applicable to all physical architectures.
Experimental quantum computing to solve systems of linear equations.
Cai, X-D; Weedbrook, C; Su, Z-E; Chen, M-C; Gu, Mile; Zhu, M-J; Li, Li; Liu, Nai-Le; Lu, Chao-Yang; Pan, Jian-Wei
2013-06-07
Solving linear systems of equations is ubiquitous in all areas of science and engineering. With rapidly growing data sets, such a task can be intractable for classical computers, as the best known classical algorithms require a time proportional to the number of variables N. A recently proposed quantum algorithm shows that quantum computers could solve linear systems in a time scale of order log(N), giving an exponential speedup over classical computers. Here we realize the simplest instance of this algorithm, solving 2×2 linear equations for various input vectors on a quantum computer. We use four quantum bits and four controlled logic gates to implement every subroutine required, demonstrating the working principle of this algorithm.
Experimental demonstration of spatial quantum correlations in multiple scattering media
DEFF Research Database (Denmark)
Smolka, Stephan; Huck, Alexander; Andersen, Ulrik Lund
2009-01-01
We demonstrate that spatial quantum correlations are induced by multiple scattering of squeezed light. The correlation relates multiple scattered photons at different spatial positions, and is tunable by varying photon fluctuations of the illuminating beam.......We demonstrate that spatial quantum correlations are induced by multiple scattering of squeezed light. The correlation relates multiple scattered photons at different spatial positions, and is tunable by varying photon fluctuations of the illuminating beam....
Experimental realization of Deutsch's algorithm in a one-way quantum computer.
Tame, M S; Prevedel, R; Paternostro, M; Böhi, P; Kim, M S; Zeilinger, A
2007-04-06
We report the first experimental demonstration of an all-optical one-way implementation of Deutsch's quantum algorithm on a four-qubit cluster state. All the possible configurations of a balanced or constant function acting on a two-qubit register are realized within the measurement-based model for quantum computation. The experimental results are in excellent agreement with the theoretical model, therefore demonstrating the successful performance of the algorithm.
Experimental quantum simulations of many-body physics with trapped ions.
Schneider, Ch; Porras, Diego; Schaetz, Tobias
2012-02-01
Direct experimental access to some of the most intriguing quantum phenomena is not granted due to the lack of precise control of the relevant parameters in their naturally intricate environment. Their simulation on conventional computers is impossible, since quantum behaviour arising with superposition states or entanglement is not efficiently translatable into the classical language. However, one could gain deeper insight into complex quantum dynamics by experimentally simulating the quantum behaviour of interest in another quantum system, where the relevant parameters and interactions can be controlled and robust effects detected sufficiently well. Systems of trapped ions provide unique control of both the internal (electronic) and external (motional) degrees of freedom. The mutual Coulomb interaction between the ions allows for large interaction strengths at comparatively large mutual ion distances enabling individual control and readout. Systems of trapped ions therefore exhibit a prominent system in several physical disciplines, for example, quantum information processing or metrology. Here, we will give an overview of different trapping techniques of ions as well as implementations for coherent manipulation of their quantum states and discuss the related theoretical basics. We then report on the experimental and theoretical progress in simulating quantum many-body physics with trapped ions and present current approaches for scaling up to more ions and more-dimensional systems.
Experimental Investigation of the Evolution of Gaussian Quantum Discord in an Open System
DEFF Research Database (Denmark)
Madsen, Lars S.; Berni, Adriano; Lassen, Mikael
2012-01-01
Gaussian quantum discord is a measure of quantum correlations in Gaussian systems. Using Gaussian discord, we quantify the quantum correlations of a bipartite entangled state and a separable two-mode mixture of coherent states. We experimentally analyze the effect of noise addition and dissipatio...... on Gaussian discord and show that the former noise degrades the discord, while the latter noise for some states leads to an increase of the discord. In particular, we experimentally demonstrate the near death of discord by noisy evolution and its revival through dissipation....
DEFF Research Database (Denmark)
Birkedal, Dan; Shah, Jagdeep; Shchegrov, Andrei V.
2000-01-01
Resonant Rayleigh scattering from quantum well excitons is investigated using ultrafast spectral interferometry. We isolate the coherent Rayleigh scattering from incoherent luminescence in a single speckle. Averaging the resonant Rayleigh intensity over several speckles allows us to identify...... features in support of quantum corrections to the classical description of the underlying scattering process....
Experimental Identification of Non-Abelian Topological Orders on a Quantum Simulator.
Li, Keren; Wan, Yidun; Hung, Ling-Yan; Lan, Tian; Long, Guilu; Lu, Dawei; Zeng, Bei; Laflamme, Raymond
2017-02-24
Topological orders can be used as media for topological quantum computing-a promising quantum computation model due to its invulnerability against local errors. Conversely, a quantum simulator, often regarded as a quantum computing device for special purposes, also offers a way of characterizing topological orders. Here, we show how to identify distinct topological orders via measuring their modular S and T matrices. In particular, we employ a nuclear magnetic resonance quantum simulator to study the properties of three topologically ordered matter phases described by the string-net model with two string types, including the Z_{2} toric code, doubled semion, and doubled Fibonacci. The third one, non-Abelian Fibonacci order is notably expected to be the simplest candidate for universal topological quantum computing. Our experiment serves as the basic module, built on which one can simulate braiding of non-Abelian anyons and ultimately, topological quantum computation via the braiding, and thus provides a new approach of investigating topological orders using quantum computers.
Experimental Investigation of Hot Carriers in Terahertz Quantum Cascade Lasers
Scamarcio, G.; Vitiello, M. S.; Spagnolo, V.
2008-03-01
The nature of the electron distribution and the electron-lattice energy relaxation phenomena in all classes of quantum cascade lasers operating in the THz range, namely, resonant-phonon, bound-to-continuum, and interlaced photon-phonon designs are reviewed. Thermalized hot-electron distributions are found in all cases. However, electronic temperatures of individual conduction subband are strongly influenced by the specific quantum design and the actual electron-lattice energy relaxation channels. A wealth of information was obtained both below and above laser threshold from the analysis of micro-probe band-to-band photoluminescence spectra recorded with a spatial resolution of ≈ 2 μm. The influence of the detailed knowledge of the hot electron distributions on the design of improved THz quantum cascade lasers aiming at high temperature operation will be discussed.
CFD Code Validation against Stratified Air-Water Flow Experimental Data
Directory of Open Access Journals (Sweden)
F. Terzuoli
2008-01-01
Full Text Available Pressurized thermal shock (PTS modelling has been identified as one of the most important industrial needs related to nuclear reactor safety. A severe PTS scenario limiting the reactor pressure vessel (RPV lifetime is the cold water emergency core cooling (ECC injection into the cold leg during a loss of coolant accident (LOCA. Since it represents a big challenge for numerical simulations, this scenario was selected within the European Platform for Nuclear Reactor Simulations (NURESIM Integrated Project as a reference two-phase problem for computational fluid dynamics (CFDs code validation. This paper presents a CFD analysis of a stratified air-water flow experimental investigation performed at the Institut de Mécanique des Fluides de Toulouse in 1985, which shares some common physical features with the ECC injection in PWR cold leg. Numerical simulations have been carried out with two commercial codes (Fluent and Ansys CFX, and a research code (NEPTUNE CFD. The aim of this work, carried out at the University of Pisa within the NURESIM IP, is to validate the free surface flow model implemented in the codes against experimental data, and to perform code-to-code benchmarking. Obtained results suggest the relevance of three-dimensional effects and stress the importance of a suitable interface drag modelling.
Experimental comparison studies with the VENUS-II disassembly code. [LMFBR
Energy Technology Data Exchange (ETDEWEB)
Bott, T.F.; Jackson, J.F.
1976-01-01
The Kiwi-TNT, SNAPTRAN-2 and SNAPTRAN-3 reactor disassembly experiments have been analyzed using the VENUS-II disassembly code. Modifications to the basic VENUS-II model required for the analysis of these tests are discussed. Key results from the analyses are compared to the experimental data and conclusions are drawn concerning the experimental validation of VENUS-II afforded by these comparisons.
Experimental demonstration of polar coded IM/DD optical OFDM for short reach system
Fang, Jiafei; Xiao, Shilin; Liu, Ling; Bi, Meihua; Zhang, Lu; Zhang, Yunhao; Hu, Weisheng
2017-11-01
In this paper, we propose a novel polar coded intensity modulation direct detection (IM/DD) optical orthogonal frequency division multiplexing (OFDM) system for short reach system. A method of evaluating the channel signal noise ratio (SNR) is proposed for soft-demodulation. The experimental results demonstrate that, compared to the conventional case, ∼9.5 dB net coding gain (NCG) at the bit error rate (BER) of 1E-3 can be achieved after 40-km standard single mode fiber (SSMF) transmission. Based on the experimental result, (512,256) polar code with low complexity and satisfactory BER performance meets the requirement of low latency in short reach system, which is a promising candidate for latency-stringent short reach optical system.
Experimental continuous-variable cloning of partial quantum information
DEFF Research Database (Denmark)
Sabuncu, Metin; Leuchs, Gerd; Andersen, Ulrik Lund
2008-01-01
The fidelity of a quantum transformation is strongly linked with the prior partial information of the state to be transformed. We illustrate this interesting point by proposing and demonstrating the superior cloning of coherent states with prior partial information. More specifically, we propose...
Experimental and quantum chemical studies on corrosion inhibition ...
Indian Academy of Sciences (India)
Abstract. The corrosion inhibition effect of fluconazole (FLU) was investigated on steel in 1 M hydrochloric acid solution. Weight loss measurements and atomic force microscope analysis were utilized to investigate the corrosion inhibition properties and film formation behaviour of FLU. Quantum chemical approach was also ...
Experimental and quantum chemical studies on corrosion inhibition ...
Indian Academy of Sciences (India)
The corrosion inhibition effect of fluconazole (FLU) was investigated on steel in 1 M hydrochloric acid solution. Weight loss measurements and atomic force microscope analysis were utilized to investigate the corrosion inhibition properties and film formation behaviour of FLU. Quantum chemical approach was also used to ...
Experimental Implementation of a Kochen-Specker Set of Quantum Tests
Directory of Open Access Journals (Sweden)
Vincenzo D’Ambrosio
2013-02-01
Full Text Available The conflict between classical and quantum physics can be identified through a series of yes-no tests on quantum systems, without it being necessary that these systems be in special quantum states. Kochen-Specker (KS sets of yes-no tests have this property and provide a quantum-versus-classical advantage that is free of the initialization problem that affects some quantum computers. Here, we report the first experimental implementation of a complete KS set that consists of 18 yes-no tests on four-dimensional quantum systems and show how to use the KS set to obtain a state-independent quantum advantage. We first demonstrate the unique power of this KS set for solving a task while avoiding the problem of state initialization. Such a demonstration is done by showing that, for 28 different quantum states encoded in the orbital-angular-momentum and polarization degrees of freedom of single photons, the KS set provides an impossible-to-beat solution. In a second experiment, we generate maximally contextual quantum correlations by performing compatible sequential measurements of the polarization and path of single photons. In this case, state independence is demonstrated for 15 different initial states. Maximum contextuality and state independence follow from the fact that the sequences of measurements project any initial quantum state onto one of the KS set’s eigenstates. Our results show that KS sets can be used for quantum-information processing and quantum computation and pave the way for future developments.
Optical coding of fusion genes using multicolor quantum dots for prostate cancer diagnosis.
Lee, Hyojin; Kim, Chloe; Lee, Dongjin; Park, Jea Ho; Searson, Peter C; Lee, Kwan Hyi
2017-01-01
Recent studies have found that prostate cancer expresses abnormal genetic markers including multiple types of TMPRSS2-ERG fusion genes. The expression level of different TMPRSS2-ERG fusion genes is correlated to pathologic variables of aggressive prostate cancer and disease progression. State-of-the-art methods for detection of TMPRSS2-ERG fusion genes include reverse transcription polymerase chain reaction (RT-PCR) with a detection limit of 1 fmol at urinary condition. RT-PCR is time consuming, costly, and inapplicable for multiplexing. Ability to identify multiple fusion genes in a single sample has become important for diagnostic and clinical purposes. There is a need for a sensitive diagnostic test to detect multiple TMPRSS2-ERG fusion genes for an early diagnosis and prognosis of prostate cancer. Here, we propose to develop an assay for prostate cancer diagnosis using oligonucleotide-functionalized quantum dot and magnetic microparticle for optical detection of rearranged TMPRSS2-ERG fusion genes at a low concentration in urine. We found that our assay was able to identify three different types of fusion gene with a wide detection range and detection limit of 1 fmol (almost the same level of the RT-PCR result reported). Here, we show detection of multiple TMPRSS2-ERG fusion genes using color-coded oligonucleotides in cell lysate and urine.
Rauch, Helmut
2015-01-01
The quantum interference of de Broglie matter waves is probably one of the most startling and fundamental aspects of quantum mechanics. It continues to tax our imaginations and leads us to new experimental windows on nature. Quantum interference phenomena are vividly displayed in the wide assembly of neutron interferometry experiments, which have been carried out since the first demonstration of a perfect silicon crystal interferometer in 1974. Since the neutron experiences all four fundamental forces of nature (strong, weak, electromagnetic, and gravitational), interferometry with neutrons provides a fertile testing ground for theory and precision measurements. Many Gedanken experiments of quantum mechanics have become real due to neutron interferometry. Quantum mechanics is a part of physics where experiment and theory are inseparably intertwined. This general theme permeates the second edition of this book. It discusses more than 40 neutron interferometry experiments along with their theoretical motivation...
Reality, locality and all that: "experimental metaphysics" and the quantum foundations
Cavalcanti, Eric G.
2008-10-01
In recent decades there has been a resurge of interest in the foundations of quantum theory, partly motivated by new experimental techniques, partly by the emerging field of quantum information science. Old questions, asked since the seminal article by Einstein, Podolsky and Rosen (EPR), are being revisited. The work of John Bell has changed the direction of investigation by recognising that those fundamental philosophical questions can have, after all, input from experiment. Abner Shimony has aptly termed this new field of enquiry "experimental metaphysics". The objective of this Thesis is to contribute to that body of research, by formalising old concepts, proposing new ones, and finding new results in well-studied areas. Without losing from sight that the appeal of experimental metaphysics comes from the adjective, every major result is followed by clear experimental proposals for quantum-atom optical setups.
Experimental scrambling and noise reduction applied to the optical encryption of QR codes.
Barrera, John Fredy; Vélez, Alejandro; Torroba, Roberto
2014-08-25
In this contribution, we implement two techniques to reinforce optical encryption, which we restrict in particular to the QR codes, but could be applied in a general encoding situation. To our knowledge, we present the first experimental-positional optical scrambling merged with an optical encryption procedure. The inclusion of an experimental scrambling technique in an optical encryption protocol, in particular dealing with a QR code "container", adds more protection to the encoding proposal. Additionally, a nonlinear normalization technique is applied to reduce the noise over the recovered images besides increasing the security against attacks. The opto-digital techniques employ an interferometric arrangement and a joint transform correlator encrypting architecture. The experimental results demonstrate the capability of the methods to accomplish the task.
Experimental ladder proof of Hardy's nonlocality for high-dimensional quantum systems
Chen, Lixiang; Zhang, Wuhong; Wu, Ziwen; Wang, Jikang; Fickler, Robert; Karimi, Ebrahim
2017-08-01
Recent years have witnessed a rapidly growing interest in high-dimensional quantum entanglement for fundamental studies as well as towards novel applications. Therefore, the ability to verify entanglement between physical qudits, d -dimensional quantum systems, is of crucial importance. To show nonclassicality, Hardy's paradox represents "the best version of Bell's theorem" without using inequalities. However, so far it has only been tested experimentally for bidimensional vector spaces. Here, we formulate a theoretical framework to demonstrate the ladder proof of Hardy's paradox for arbitrary high-dimensional systems. Furthermore, we experimentally demonstrate the ladder proof by taking advantage of the orbital angular momentum of high-dimensionally entangled photon pairs. We perform the ladder proof of Hardy's paradox for dimensions 3 and 4, both with the ladder up to the third step. Our paper paves the way towards a deeper understanding of the nature of high-dimensionally entangled quantum states and may find applications in quantum information science.
Experimental investigation of a four-qubit linear-optical quantum logic circuit.
Stárek, R; Mičuda, M; Miková, M; Straka, I; Dušek, M; Ježek, M; Fiurášek, J
2016-09-20
We experimentally demonstrate and characterize a four-qubit linear-optical quantum logic circuit. Our robust and versatile scheme exploits encoding of two qubits into polarization and path degrees of single photons and involves two crossed inherently stable interferometers. This approach allows us to design a complex quantum logic circuit that combines a genuine four-qubit C(3)Z gate and several two-qubit and single-qubit gates. The C(3)Z gate introduces a sign flip if and only if all four qubits are in the computational state |1〉. We verify high-fidelity performance of this central four-qubit gate using Hofmann bounds on quantum gate fidelity and Monte Carlo fidelity sampling. We also experimentally demonstrate that the quantum logic circuit can generate genuine multipartite entanglement and we certify the entanglement with the use of suitably tailored entanglement witnesses.
Experimental circular quantum secret sharing over telecom fiber network.
Wei, Ke-Jin; Ma, Hai-Qiang; Yang, Jian-Hui
2013-07-15
We present a robust single photon circular quantum secret sharing (QSS) scheme with phase encoding over 50 km single mode fiber network using a circular QSS protocol. Our scheme can automatically provide a perfect compensation of birefringence and remain stable for a long time. A high visibility of 99.3% is obtained. Furthermore, our scheme realizes a polarization insensitive phase modulators. The visibility of this system can be maintained perpetually without any adjustment to the system every time we test the system.
Wu, Menglong; Han, Dahai; Zhang, Xiang; Zhang, Feng; Zhang, Min; Yue, Guangxin
2014-03-10
We have implemented a modified Low-Density Parity-Check (LDPC) codec algorithm in ultraviolet (UV) communication system. Simulations are conducted with measured parameters to evaluate the LDPC-based UV system performance. Moreover, LDPC (960, 480) and RS (18, 10) are implemented and experimented via a non-line-of-sight (NLOS) UV test bed. The experimental results are in agreement with the simulation and suggest that based on the given power and 10(-3)bit error rate (BER), in comparison with an uncoded system, average communication distance increases 32% with RS code, while 78% with LDPC code.
Simulation and experimental research on the Alamouti code for ultraviolet communication
Guo, Li; Liu, Kunlun; Meng, Dedan; Mu, Xidong; Han, Dahai
2016-01-01
The Alamouti code can obtain the diversity gain utilizing the transmitting signal orthogonally without the use of a complicated decoding scheme. The modified Alamouti code for the ultraviolet (UV) communication system is studied in theoretical analysis, MATLAB® simulation, and offline experiment. The theoretical analysis and simulation results indicate that the usage of the Alamouti code in the UV communication system can achieve a higher diversity gain and reduce the system bit error rate more effectively than the single-input single-output and single-input multiple-output technologies. The experiments were performed to verify the simulation results. Next, we analyzed the discrepancy between the simulation results and the experimental results. These studies are helpful for UV multiple-input multiple-output communication system design and implementation.
Experimental realization of a one-way quantum computer algorithm solving Simon's problem.
Tame, M S; Bell, B A; Di Franco, C; Wadsworth, W J; Rarity, J G
2014-11-14
We report an experimental demonstration of a one-way implementation of a quantum algorithm solving Simon's problem-a black-box period-finding problem that has an exponential gap between the classical and quantum runtime. Using an all-optical setup and modifying the bases of single-qubit measurements on a five-qubit cluster state, key representative functions of the logical two-qubit version's black box can be queried and solved. To the best of our knowledge, this work represents the first experimental realization of the quantum algorithm solving Simon's problem. The experimental results are in excellent agreement with the theoretical model, demonstrating the successful performance of the algorithm. With a view to scaling up to larger numbers of qubits, we analyze the resource requirements for an n-qubit version. This work helps highlight how one-way quantum computing provides a practical route to experimentally investigating the quantum-classical gap in the query complexity model.
Thermalization, Freeze-out, and Noise: Deciphering Experimental Quantum Annealers
Marshall, Jeffrey; Rieffel, Eleanor G.; Hen, Itay
2017-12-01
By contrasting the performance of two quantum annealers operating at different temperatures, we address recent questions related to the role of temperature in these devices and their function as "Boltzmann samplers." Using a method to reliably calculate the degeneracies of the energy levels of large-scale spin-glass instances, we are able to estimate the instance-dependent effective temperature from the output of annealing runs. Our results corroborate the "freeze-out" picture which posits two regimes, one in which the final state corresponds to a Boltzmann distribution of the final Hamiltonian with a well-defined "effective temperature" determined at a freeze-out point late in the annealing schedule, and another regime in which such a distribution is not necessarily expected. We find that the output distributions of the annealers do not, in general, correspond to a classical Boltzmann distribution for the final Hamiltonian. We also find that the effective temperatures at different programing cycles fluctuate greatly, with the effect worsening with problem size. We discuss the implications of our results for the design of future quantum annealers to act as more-effective Boltzmann samplers and for the programing of such annealers.
Sisodia, Mitali; Shukla, Abhishek; Thapliyal, Kishore; Pathak, Anirban
2017-12-01
An explicit scheme (quantum circuit) is designed for the teleportation of an n-qubit quantum state. It is established that the proposed scheme requires an optimal amount of quantum resources, whereas larger amount of quantum resources have been used in a large number of recently reported teleportation schemes for the quantum states which can be viewed as special cases of the general n-qubit state considered here. A trade-off between our knowledge about the quantum state to be teleported and the amount of quantum resources required for the same is observed. A proof-of-principle experimental realization of the proposed scheme (for a 2-qubit state) is also performed using 5-qubit superconductivity-based IBM quantum computer. The experimental results show that the state has been teleported with high fidelity. Relevance of the proposed teleportation scheme has also been discussed in the context of controlled, bidirectional, and bidirectional controlled state teleportation.
DEFF Research Database (Denmark)
Pedersen, Thomas Garm; Ramanujam, P.S.; Johansen, P.M.
1998-01-01
The microscopic properties of azobenzene chromophores are important for a correct description of optical storage systems based on photoinduced anisotropy in azobenzene polymers. A quantum model of these properties is presented and verified by comparison to experimental absorption spectra for trans...... and cis isomers of cyano methoxy azobenzene. In addition, the trans --> cis quantum efficiency is measured, and hence the combined experimental and theoretical work allows one to determine the essential molecular properties, including magnitude and anisotropy of the absorption cross section and various...
Ethics in human experimentation: the two military physicians who helped develop the Nuremberg Code.
Temme, Leonard A
2003-12-01
The Nuremberg Code is generally considered the beginning of modern ethics in human experimentation. The Code is a list of 10 principles that Judge Walter Beals included in the judgment he delivered at the close of the Nuremberg Medical Trial on 19 August 1947. Recently, scholars have studied the origin of the Code, who wrote it, and why. This is important to military medicine and the Aerospace Medical Association in particular because many of the defendants claimed their crimes were experiments in aviation and environmental physiology conducted under wartime conditions. The chief prosecutor of the Nuremberg Medical Trial, General Telford Taylor, relied on the guidance of an advisor provided by the American Medical Association, Andrew C. Ivy, one of the foremost physiologists of his time. The neurologist, Leo Alexander, then a colonel in the U.S. Army Reserves, was another medical advisor. Both men were crucial to the development of Taylor's courtroom strategy. The material Alexander and Ivy provided was incorporated verbatim in the section of the judgment that became the Code. Although both men contributed to the Code, Ivy provided what seems to be the first formulation of many of these principles during a meeting of Allied medical investigators at the Pasteur Institute in July 1946. Naval researchers should note that Ivy had been the Director of the Research Division of the Naval Medical Research Institute when it was commissioned on October 27, 1942.
Coded 8-PSK experimental modem for the Intelsat SCPC-system
Ungerboeck, G.; Hagenauer, J.; Abdel-Nabi, T.
Following a review of the theoretical aspects of coded octal PSK (C8PSK) modulation, this paper reports on the practical implementation features of an experimental 64 kbit/s C8PSK modem developed under INTELSAT R&D funding. Results of extensive laboratory and satellite tests are documented and analyzed. Finally, the applicability of C8PSK to present future INTELSAT networks is discussed.
Experimental considerations for quantum-entanglement studies with relativistic fermions
Energy Technology Data Exchange (ETDEWEB)
Schlemme, Steffen; Peck, Marius; Enders, Joachim [TU Darmstadt (Germany); Bodek, Kazimierz; Rozpedzik, Dagmara; Zejma, Jacek [Jagiellonian University, Cracow (Poland); Caban, Pawel; Rembielinski, Jakub [University of Lodz, Lodz (Poland); Ciborowski, Jacek; Dragowski, Michal; Wlodarczyk, Marta [Warsaw University, Warsaw (Poland); Kozela, Adam [Institute of Nuclear Physics, PAS, Cracow (Poland)
2015-07-01
The QUEST (Quantum entanglement of Ultra-relativistic Electrons in Singlet and Triplet states) project is aimed at the determination of the electron spin correlation function at relativistic energies. Electron pairs are created through Moeller scattering, and polarization observables are planned to be measured in Mott scattering. The predicted spin correlation function is energy dependent with values of several per cent at energies of 10-20 MeV. The results of a first test experiment at the S-DALINAC were not sensitive enough to detect entangled and Mott-scattered electron pairs at the expected energies. Further steps are either to improve the former setup or design a new polarimeter for lower energies to improve statistics due to the higher scattering cross sections. This contribution presents general considerations, test results, and an outlook.
Surface Traps in Colloidal Quantum Dots: A Combined Experimental and Theoretical Perspective.
Giansante, Carlo; Infante, Ivan
2017-10-19
Surface traps are ubiquitous to nanoscopic semiconductor materials. Understanding their atomistic origin and manipulating them chemically have capital importance to design defect-free colloidal quantum dots and make a leap forward in the development of efficient optoelectronic devices. Recent advances in computing power established computational chemistry as a powerful tool to describe accurately complex chemical species and nowadays it became conceivable to model colloidal quantum dots with realistic sizes and shapes. In this Perspective, we combine the knowledge gathered in recent experimental findings with the computation of quantum dot electronic structures. We analyze three different systems: namely, CdSe, PbS, and CsPbI3 as benchmark semiconductor nanocrystals showing how different types of trap states can form at their surface. In addition, we suggest experimental healing of such traps according to their chemical origin and nanocrystal composition.
Physics-based mathematical models for quantum devices via experimental system identification
Energy Technology Data Exchange (ETDEWEB)
Schirmer, S G; Oi, D K L; Devitt, S J [Department of Applied Maths and Theoretical Physics, University of Cambridge, Wilberforce Rd, Cambridge, CB3 0WA (United Kingdom); SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom); National Institute of Informatics, 2-1-2 Hitotsubashi, Chiyoda-ku, Tokyo 101-8430 (Japan)], E-mail: sgs29@cam.ac.uk
2008-03-15
We consider the task of intrinsic control system identification for quantum devices. The problem of experimental determination of subspace confinement is considered, and simple general strategies for full Hamiltonian identification and decoherence characterization of a controlled two-level system are presented.
Licos, a fuel performance code for innovative fuel elements or experimental devices design
Energy Technology Data Exchange (ETDEWEB)
Helfer, Thomas, E-mail: thomas.helfer@cea.fr; Bejaoui, Syriac, E-mail: syriac.bejaoui@cea.fr; Michel, Bruno, E-mail: bruno.michel@cea.fr
2015-12-01
Highlights: • The Licos fuel performance code is introduced. • Advanced features, such as dependency algorithm and kriging are described. • First results on three dimensional modelling of the SFR fuel pin are given. • Application to the DIAMINO design computations is discussed. - Abstract: This paper provides an overview of the Licos fuel performance code which has been developed for several years within the platform pleiades, co-developed by the French Alternative Energies and Atomic Energy Commission (CEA) and its industrial partners Électricité de France (EDF) and AREVA. CEA engineers have been using Licos to back multidimensional thermo-mechanical studies on innovative fuel elements design and experimental device pre-and post-irradiation computations. Studies made with Licos thus encompass a wide range of situations, including most nuclear systems used or studied in France in recent years (PWR, SFR or GFR), normal and off-normal operating conditions, and a large selection of materials (either for fuel, absorber, coolant and cladding). The aim of this paper is to give some insights about some innovative features in the design of Licos (dependency management, kriging, mfront, etc.). We also present two studies that demonstrate the flexibility of this code. The first one shows how Licos can be combined with the Germinal monodimensional fuel performance code to demonstrate the interest of a three dimensional modelling of the fuel relocation phenomenon in the Sodium Fast Reactor fuel pin. The second one describes how Licos was used to model the DIAMINO experiment.
Experimental characterization of a quantum many-body system via higher-order correlations
Schweigler, Thomas; Kasper, Valentin; Erne, Sebastian; Mazets, Igor; Rauer, Bernhard; Cataldini, Federica; Langen, Tim; Gasenzer, Thomas; Berges, Jürgen; Schmiedmayer, Jörg
2017-05-01
Quantum systems can be characterized by their correlations. Higher-order (larger than second order) correlations, and the ways in which they can be decomposed into correlations of lower order, provide important information about the system, its structure, its interactions and its complexity. The measurement of such correlation functions is therefore an essential tool for reading, verifying and characterizing quantum simulations. Although higher-order correlation functions are frequently used in theoretical calculations, so far mainly correlations up to second order have been studied experimentally. Here we study a pair of tunnel-coupled one-dimensional atomic superfluids and characterize the corresponding quantum many-body problem by measuring correlation functions. We extract phase correlation functions up to tenth order from interference patterns and analyse whether, and under what conditions, these functions factorize into correlations of lower order. This analysis characterizes the essential features of our system, the relevant quasiparticles, their interactions and topologically distinct vacua. From our data we conclude that in thermal equilibrium our system can be seen as a quantum simulator of the sine-Gordon model, relevant for diverse disciplines ranging from particle physics to condensed matter. The measurement and evaluation of higher-order correlation functions can easily be generalized to other systems and to study correlations of any other observable such as density, spin and magnetization. It therefore represents a general method for analysing quantum many-body systems from experimental data.
Directory of Open Access Journals (Sweden)
Karfopoulos Konstantinos L.
2014-01-01
Full Text Available The determination of 235U in environmental samples from its 185.72 keV photons may require the deconvolution of the multiplet photopeak at ~186 keV, due to the co-existence of the 186.25 keV photons of 226Ra in the spectrum. Successful deconvolution depends on many parameters, such as the detector characteristics, the activity concentration of the 235U and 226Ra in the sample, the background continuum in the 186 keV energy region and the gamma-spectrometry computer code used. In this work two sets of experimental test spectra were constructed for examining the deconvolution of the multiplet photopeak performed by different codes. For the construction of the test spectra, a high-resolution low energy germanium detector was used. The first series consists of 140 spectra and simulates environmental samples containing various activity concentration levels of 235U and 226Ra. The second series consists of 280 spectra and has been derived by adding 137Cs, corresponding to various activity concentration levels, to specific first series test spectra. As the 137Cs backscatter edge is detected in the energy region of the multiplet photopeak at ~186 keV, this second series of test spectra tests the analysis of the multiplet photopeak in high background continuum conditions. The analysis of the test spectra is performed by two different g-spectrometry analysis codes: (a spectrum unix analysis code, a computer code developed in-house and (b analysis of germanium detector spectra, a program freely available from the IAEA. The results obtained by the two programs are compared in terms of photopeak detection and photopeak area determination.
Experimental investigation of spin-orbit coupling in n-type PbTe quantum wells
Energy Technology Data Exchange (ETDEWEB)
Peres, M. L.; Monteiro, H. S.; Castro, S. de [Institute of Physics and Chemistry, Federal University of Itajubá, PB 50, 37500-903 Itajubá, MG (Brazil); Chitta, V. A.; Oliveira, N. F. [Institute of Physics, University of São Paulo, PB 66318, 05315-970 São Paulo, SP (Brazil); Mengui, U. A.; Rappl, P. H. O.; Abramof, E. [Laboratório Associado de Sensores e Materiais, Instituto Nacional de Pesquisas Espaciais, PB 515, 12201-970 São José dos Campos, SP (Brazil); Maude, D. K. [Grenoble High Magnetic Field Laboratory, CNRS, BP 166, 38042 Grenoble Cedex 9 (France)
2014-03-07
The spin-orbit coupling is studied experimentally in two PbTe quantum wells by means of weak antilocalization effect. Using the Hikami-Larkin-Nagaoka model through a computational global optimization procedure, we extracted the spin-orbit and inelastic scattering times and estimated the strength of the zero field spin-splitting energy Δ{sub so}. The values of Δ{sub so} are linearly dependent on the Fermi wave vector (k{sub F}) confirming theoretical predictions of the existence of large spin-orbit coupling in IV-VI quantum wells originated from pure Rashba effect.
Experimentally modeling stochastic processes with less memory by the use of a quantum processor.
Palsson, Matthew S; Gu, Mile; Ho, Joseph; Wiseman, Howard M; Pryde, Geoff J
2017-02-01
Computer simulation of observable phenomena is an indispensable tool for engineering new technology, understanding the natural world, and studying human society. However, the most interesting systems are often so complex that simulating their future behavior demands storing immense amounts of information regarding how they have behaved in the past. For increasingly complex systems, simulation becomes increasingly difficult and is ultimately constrained by resources such as computer memory. Recent theoretical work shows that quantum theory can reduce this memory requirement beyond ultimate classical limits, as measured by a process' statistical complexity, C. We experimentally demonstrate this quantum advantage in simulating stochastic processes. Our quantum implementation observes a memory requirement of Cq = 0.05 ± 0.01, far below the ultimate classical limit of C = 1. Scaling up this technique would substantially reduce the memory required in simulations of more complex systems.
Experimental demonstration of real-time adaptive one-qubit quantum-state tomography
Yin, Qi; Li, Li; Xiang, Xiao; Xiang, Guo-Yong; Li, Chuang-Feng; Guo, Guang-Can
2017-01-01
Quantum-state tomography plays a pivotal role in quantum computation and information processing. To improve the accuracy in estimating an unknown state, carefully designed measurement schemes, such as adopting an adaptive strategy, are necessarily needed, which have gained great interest recently. In this work, based on the proposal of Sugiyama et al. [Phys. Rev. A 85, 052107 (2012)], 10.1103/PhysRevA.85.052107, we experimentally realize an adaptive quantum-state tomography for one qubit in an optical system. Since this scheme gives an analytical solution to the optimal measurement basis problem, our experiment is updated in real time and the infidelity between the real state and the estimated state is tracked with the detected photons. We observe an almost 1 /N scaling rule of averaged infidelity against the overall number of photons, N , in our experiment, which outperforms 1 /√{N } of nonadaptive schemes.
Clarke, Patrick J; Collins, Robert J; Dunjko, Vedran; Andersson, Erika; Jeffers, John; Buller, Gerald S
2012-01-01
Digital signatures are frequently used in data transfer to prevent impersonation, repudiation and message tampering. Currently used classical digital signature schemes rely on public key encryption techniques, where the complexity of so-called 'one-way' mathematical functions is used to provide security over sufficiently long timescales. No mathematical proofs are known for the long-term security of such techniques. Quantum digital signatures offer a means of sending a message, which cannot be forged or repudiated, with security verified by information-theoretical limits and quantum mechanics. Here we demonstrate an experimental system, which distributes quantum signatures from one sender to two receivers and enables message sending ensured against forging and repudiation. Additionally, we analyse the security of the system in some typical scenarios. Our system is based on the interference of phase-encoded coherent states of light and our implementation utilizes polarization-maintaining optical fibre and photons with a wavelength of 850 nm.
Sisodia, Mitali; Shukla, Abhishek; Pathak, Anirban
2017-12-01
A scheme for distributed quantum measurement that allows nondestructive or indirect Bell measurement was proposed by Gupta et al [1]. In the present work, Gupta et al.'s scheme is experimentally realized using the five-qubit super-conductivity-based quantum computer, which has been recently placed in cloud by IBM Corporation. The experiment confirmed that the Bell state can be constructed and measured in a nondestructive manner with a reasonably high fidelity. A comparison of the outcomes of this study and the results obtained earlier in an NMR-based experiment (Samal et al. (2010) [10]) has also been performed. The study indicates that to make a scalable SQUID-based quantum computer, errors introduced by the gates (in the present technology) have to be reduced considerably.
Experimentally modeling stochastic processes with less memory by the use of a quantum processor
Palsson, Matthew S.; Gu, Mile; Ho, Joseph; Wiseman, Howard M.; Pryde, Geoff J.
2017-01-01
Computer simulation of observable phenomena is an indispensable tool for engineering new technology, understanding the natural world, and studying human society. However, the most interesting systems are often so complex that simulating their future behavior demands storing immense amounts of information regarding how they have behaved in the past. For increasingly complex systems, simulation becomes increasingly difficult and is ultimately constrained by resources such as computer memory. Recent theoretical work shows that quantum theory can reduce this memory requirement beyond ultimate classical limits, as measured by a process’ statistical complexity, C. We experimentally demonstrate this quantum advantage in simulating stochastic processes. Our quantum implementation observes a memory requirement of Cq = 0.05 ± 0.01, far below the ultimate classical limit of C = 1. Scaling up this technique would substantially reduce the memory required in simulations of more complex systems. PMID:28168218
Experimental implementation of a quantum walk on a circle with single photons
Bian, Zhi-Hao; Li, Jian; Zhan, Xiang; Twamley, Jason; Xue, Peng
2017-05-01
We experimentally implement a quantum walk on a circle in position space. Using a different arrangement of linear optical elements, our experiment realizes clockwise-cycling and counterclockwise-cycling walks. Periodic evolutions in quantum walks on three- and four-node circles with uniform coin flipping for each step and a localized initial walker state are observed, and the full revival of the walker+coin state occurs. Coherent information encoded in the coin state shows the periodic collapse and revival due to the interaction between the coin and walker. The technology to realize clockwise-cycling and counterclockwise-cycling walks can be expanded to simulate a quantum walk on a circle with arbitrary nodes.
Experimental benchmark and code validation for airfoils equipped with passive vortex generators
Baldacchino, D.; Manolesos, M.; Ferreira, C.; González Salcedo, Á.; Aparicio, M.; Chaviaropoulos, T.; Diakakis, K.; Florentie, L.; García, N. R.; Papadakis, G.; Sørensen, N. N.; Timmer, N.; Troldborg, N.; Voutsinas, S.; van Zuijlen, A.
2016-09-01
Experimental results and complimentary computations for airfoils with vortex generators are compared in this paper, as part of an effort within the AVATAR project to develop tools for wind turbine blade control devices. Measurements from two airfoils equipped with passive vortex generators, a 30% thick DU97W300 and an 18% thick NTUA T18 have been used for benchmarking several simulation tools. These tools span low-to-high complexity, ranging from engineering-level integral boundary layer tools to fully-resolved computational fluid dynamics codes. Results indicate that with appropriate calibration, engineering-type tools can capture the effects of vortex generators and outperform more complex tools. Fully resolved CFD comes at a much higher computational cost and does not necessarily capture the increased lift due to the VGs. However, in lieu of the limited experimental data available for calibration, high fidelity tools are still required for assessing the effect of vortex generators on airfoil performance.
Experimental benchmark and code validation for airfoils equipped with passive vortex generators
DEFF Research Database (Denmark)
Baldacchino, D.; Manolesos, M.; Ferreira, Célia Maria Dias
2016-01-01
Experimental results and complimentary computations for airfoils with vortex generators are compared in this paper, as part of an effort within the AVATAR project to develop tools for wind turbine blade control devices. Measurements from two airfoils equipped with passive vortex generators, a 30......% thick DU97W300 and an 18% thick NTUA T18 have been used for benchmarking several simulation tools. These tools span low-to-high complexity, ranging from engineering-level integral boundary layer tools to fully-resolved computational fluid dynamics codes. Results indicate that with appropriate...... calibration, engineering-type tools can capture the effects of vortex generators and outperform more complex tools. Fully resolved CFD comes at a much higher computational cost and does not necessarily capture the increased lift due to the VGs. However, in lieu of the limited experimental data available...
Experimental validation of response function of a NaI (Tl) detector modeled with Monte Carlo codes
Hajheidari, M. T.; Safari, M. J.; Afarideh, H.; Rouhi, H.
2016-06-01
This paper reports on the simulation of the response function of a Ø3"× 3" NaI (Tl) detector, using the FLUKA and MCNPX codes. These models were validated against extensive experimental data and used to benchmark various aspects of the response function. Comparisons show good agreement between both codes and experiments for different geometrical arrangements and gamma-ray energies.
Energy Technology Data Exchange (ETDEWEB)
Xu, X Q
2001-08-09
A boundary plasma turbulence code BOUT is presented. The preliminary encouraging results have been obtained when comparing with probe measurements for a typical Ohmic discharge in CT-7 tokamak. The validation and benchmark of BOUT code and experimental diagnostic tools for fusion boundary plasma turbulence is proposed.
Directory of Open Access Journals (Sweden)
Martin Bercx, Florian Goth, Johannes S. Hofmann, Fakher F. Assaad
2017-08-01
Full Text Available The Algorithms for Lattice Fermions package provides a general code for the finite temperature auxiliary field quantum Monte Carlo algorithm. The code is engineered to be able to simulate any model that can be written in terms of sums of single-body operators, of squares of single-body operators and single-body operators coupled to an Ising field with given dynamics. We provide predefined types that allow the user to specify the model, the Bravais lattice as well as equal time and time displaced observables. The code supports an MPI implementation. Examples such as the Hubbard model on the honeycomb lattice and the Hubbard model on the square lattice coupled to a transverse Ising field are provided and discussed in the documentation. We furthermore discuss how to use the package to implement the Kondo lattice model and the $SU(N$-Hubbard-Heisenberg model. One can download the code from our Git instance at https://alf.physik.uni-wuerzburg.de and sign in to file issues.
2011-01-01
Background Complete and accurate genome annotation is crucial for comprehensive and systematic studies of biological systems. However, determining protein-coding genes for most new genomes is almost completely performed by inference using computational predictions with significant documented error rates (> 15%). Furthermore, gene prediction programs provide no information on biologically important post-translational processing events critical for protein function. Results We experimentally annotated the bacterial pathogen Salmonella Typhimurium 14028, using "shotgun" proteomics to accurately uncover the translational landscape and post-translational features. The data provide protein-level experimental validation for approximately half of the predicted protein-coding genes in Salmonella and suggest revisions to several genes that appear to have incorrectly assigned translational start sites, including a potential novel alternate start codon. Additionally, we uncovered 12 non-annotated genes missed by gene prediction programs, as well as evidence suggesting a role for one of these novel ORFs in Salmonella pathogenesis. We also characterized post-translational features in the Salmonella genome, including chemical modifications and proteolytic cleavages. We find that bacteria have a much larger and more complex repertoire of chemical modifications than previously thought including several novel modifications. Our in vivo proteolysis data identified more than 130 signal peptide and N-terminal methionine cleavage events critical for protein function. Conclusion This work highlights several ways in which application of proteomics data can improve the quality of genome annotations to facilitate novel biological insights and provides a comprehensive proteome map of Salmonella as a resource for systems analysis. PMID:21867535
Energy Technology Data Exchange (ETDEWEB)
Ansong, Charles; Tolic, Nikola; Purvine, Samuel O.; Porwollik, Steffen; Jones, Marcus B.; Yoon, Hyunjin; Payne, Samuel H.; Martin, Jessica L.; Burnet, Meagan C.; Monroe, Matthew E.; Venepally, Pratap; Smith, Richard D.; Peterson, Scott; Heffron, Fred; Mcclelland, Michael; Adkins, Joshua N.
2011-08-25
Complete and accurate genome annotation is crucial for comprehensive and systematic studies of biological systems. For example systems biology-oriented genome scale modeling efforts greatly benefit from accurate annotation of protein-coding genes to develop proper functioning models. However, determining protein-coding genes for most new genomes is almost completely performed by inference, using computational predictions with significant documented error rates (> 15%). Furthermore, gene prediction programs provide no information on biologically important post-translational processing events critical for protein function. With the ability to directly measure peptides arising from expressed proteins, mass spectrometry-based proteomics approaches can be used to augment and verify coding regions of a genomic sequence and importantly detect post-translational processing events. In this study we utilized “shotgun” proteomics to guide accurate primary genome annotation of the bacterial pathogen Salmonella Typhimurium 14028 to facilitate a systems-level understanding of Salmonella biology. The data provides protein-level experimental confirmation for 44% of predicted protein-coding genes, suggests revisions to 48 genes assigned incorrect translational start sites, and uncovers 13 non-annotated genes missed by gene prediction programs. We also present a comprehensive analysis of post-translational processing events in Salmonella, revealing a wide range of complex chemical modifications (70 distinct modifications) and confirming more than 130 signal peptide and N-terminal methionine cleavage events in Salmonella. This study highlights several ways in which proteomics data applied during the primary stages of annotation can improve the quality of genome annotations, especially with regards to the annotation of mature protein products.
Peterson, J P S; Sarthour, R S; Souza, A M; Oliveira, I S; Goold, J; Modi, K; Soares-Pinto, D O; Céleri, L C
2016-04-01
Landauer's principle sets fundamental thermodynamical constraints for classical and quantum information processing, thus affecting not only various branches of physics, but also of computer science and engineering. Despite its importance, this principle was only recently experimentally considered for classical systems. Here we employ a nuclear magnetic resonance set-up to experimentally address the information to energy conversion in a quantum system. Specifically, we consider a three nuclear spins [Formula: see text] (qubits) molecule-the system, the reservoir and the ancilla-to measure the heat dissipated during the implementation of a global system-reservoir unitary interaction that changes the information content of the system. By employing an interferometric technique, we were able to reconstruct the heat distribution associated with the unitary interaction. Then, through quantum state tomography, we measured the relative change in the entropy of the system. In this way, we were able to verify that an operation that changes the information content of the system must necessarily generate heat in the reservoir, exactly as predicted by Landauer's principle. The scheme presented here allows for the detailed study of irreversible entropy production in quantum information processors.
Experimental Test of the State Estimation-Reversal Tradeoff Relation in General Quantum Measurements
Directory of Open Access Journals (Sweden)
Geng Chen
2014-06-01
Full Text Available When a measurement has limited strength, only partial information, regarding the initial state, is extracted, and, correspondingly, there is a probability to reverse its effect on the system and retrieve the original state. Recently, a clear and direct quantitative description of this complementary relationship, in terms of a tradeoff relation, was developed by Y. K. Cheong and S. W. Lee. [Phys. Rev. Lett. 109, 150402 (2012]. Here, this tradeoff relation is experimentally verified using polarization-encoded single photons from a quantum dot. Measurement operators representing a complete range, from not affecting the system to a projection to a single polarization state, are realized. In addition, for each measurement operator, an optimal reversal operator is also implemented. The upper bound of the tradeoff relation is mapped to experimental parameters representing the measurement strength. Our results complement the theoretical work and provide a hands-on characterization of general quantum measurements.
Experimental Tests of Quantum Mechanics: Pauli Exclusion Principle and Spontaneous Collapse Models
Petrascu, Catalina Curceanu; Bragadireanu, Mario; Clozza, Alberto; Guaraldo, Carlo; Iliescu, Mihai; Rizzo, Alessandro; Vidal, Antonio Romero; Scordo, Alessandro; Sirghi, Diana Laura; Sirghi, Florin; Sperandio, Laura; Doce, Oton Vazquez; Bassi, Angelo; Donadi, Sandro; Milotti, Edoardo; Laubenstein, Matthias; Bertolucci, Sergio; Bragadireanu, Mario; Curceanu, Catalina; Pietreanu, Dorel; Ponta, Titus; Cargnelli, Michael; Ishiwatari, Tomoichi; Marton, Johann; Widmann, Eberhard; Zmeskal, Johann; Matteo, Sergio di; Egger, Jean Pierre
2014-01-01
The Pauli exclusion principle (PEP), as a consequence or the spin-statistics connection, is one of the basic principles of the modern physics. Being at the very basis of our understanding of matter, it spurs a lively debate on its possible limits, deeply rooted as it is in the very foundations of Quantum Field Theory. The VIP (VIolation of the Pauli exclusion principle) experiment is searching for a possible small violation of the PEP for electrons, using the method of searching for Pauli Exclusion Principle forbidden atomic transitions in copper. We describe the experimental method and the obtained results; we briefly present future plans to go beyond the actual limit by upgrading the experiment using vetoed new spectroscopic fast Silicon Drift Detectors. We also mention the possibility of using a similar experimental technique to search for possible X-rays generated in the spontaneous collapse models of quantum mechanics.
Algorithms and computer codes for atomic and molecular quantum scattering theory
Energy Technology Data Exchange (ETDEWEB)
Thomas, L. (ed.)
1979-01-01
This workshop has succeeded in bringing up 11 different coupled equation codes on the NRCC computer, testing them against a set of 24 different test problems and making them available to the user community. These codes span a wide variety of methodologies, and factors of up to 300 were observed in the spread of computer times on specific problems. A very effective method was devised for examining the performance of the individual codes in the different regions of the integration range. Many of the strengths and weaknesses of the codes have been identified. Based on these observations, a hybrid code has been developed which is significantly superior to any single code tested. Thus, not only have the original goals been fully met, the workshop has resulted directly in an advancement of the field. All of the computer programs except VIVS are available upon request from the NRCC. Since an improved version of VIVS is contained in the hybrid program, VIVAS, it was not made available for distribution. The individual program LOGD is, however, available. In addition, programs which compute the potential energy matrices of the test problems are also available. The software library names for Tests 1, 2 and 4 are HEH2, LICO, and EN2, respectively.
Collins, Robert J.; Amiri, Ryan; Fujiwara, Mikio; Honjo, Toshimori; Shimizu, Kaoru; Tamaki, Kiyoshi; Takeoka, Masahiro; Andersson, Erika; Buller, Gerald S.; Sasaki, Masahide
2016-11-01
Quantum digital signatures apply quantum mechanics to the problem of guaranteeing message integrity and non-repudiation with information-theoretical security, which are complementary to the confidentiality realized by quantum key distribution. Previous experimental demonstrations have been limited to transmission distances of less than 5-km of optical fiber in a laboratory setting. Here we report the first demonstration of quantum digital signatures over installed optical fiber as well as the longest transmission link reported to date. This demonstration used a 90-km long differential phase shift quantum key distribution system to achieve approximately one signed bit per second - an increase in the signature generation rate of several orders of magnitude over previous optical fiber demonstrations.
Reliable quantum communication over a quantum relay channel
Energy Technology Data Exchange (ETDEWEB)
Gyongyosi, Laszlo, E-mail: gyongyosi@hit.bme.hu [Quantum Technologies Laboratory, Department of Telecommunications, Budapest University of Technology and Economics, 2 Magyar tudosok krt, Budapest, H-1117, Hungary and Information Systems Research Group, Mathematics and Natural Sciences, Hungarian Ac (Hungary); Imre, Sandor [Quantum Technologies Laboratory, Department of Telecommunications, Budapest University of Technology and Economics, 2 Magyar tudosok krt, Budapest, H-1117 (Hungary)
2014-12-04
We show that reliable quantum communication over an unreliable quantum relay channels is possible. The coding scheme combines the results on the superadditivity of quantum channels and the efficient quantum coding approaches.
Energy Technology Data Exchange (ETDEWEB)
Beljaev, Y.V.; Zaitsev, S.I.; Tarankov, G.A. [OKB Gidropress (Russian Federation)
1995-12-31
Comparison of the results of calculational analysis with experimental data on water level behaviour in horizontal steam generator (PGV-440) under the conditions with cessation of feedwater supply is presented in the report. Calculational analysis is performed using DIMANIKA-5 code, experimental data are obtained at Kola NPP-4. (orig.). 2 refs.
An experimental infrared sensor using adaptive coded apertures for enhanced resolution
Gordon, Neil T.; de Villiers, Geoffrey D.; Ridley, Kevin D.; Bennett, Charlotte R.; McNie, Mark E.; Proudler, Ian K.; Russell, Lee; Slinger, Christopher W.; Gilholm, Kevin
2010-08-01
Adaptive coded aperture imaging (ACAI) has the potential to enhance greatly the performance of sensing systems by allowing sub detector pixel image and tracking resolution. A small experimental system has been set up to allow the practical demonstration of these benefits in the mid infrared, as well as investigating the calibration and stability of the system. The system can also be used to test modeling of similar ACAI systems in the infrared. The demonstrator can use either a set of fixed masks or a novel MOEMS adaptive transmissive spatial light modulator. This paper discusses the design and testing of the system including the development of novel decoding algorithms and some initial imaging results are presented.
Fuel model Validation in the TASS/SMR-S code by Comparing with Experimental Results
Energy Technology Data Exchange (ETDEWEB)
Ahn, Sang Jun; Yang, Soo Hyung; Chung, Young Jong; Lee, Won Jae [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2011-05-15
An advanced integral pressurized water reactor, SMART (System-Integrated Modular Advanced ReacTor) has been developed by KAERI (Korea Atomic Energy Research and Institute). For the purpose of an electric power generation and seawater desalination by using nuclear energy, SMART has been developed by KAERI (KAERI, 2010). For the safety evaluation and performance analysis of the SMART, TASS/SMR-S (Transient And Setpoint Simulation/System- integrated Modular Reactor) code, has been developed. In this paper, the gap conductance model for the calculation of gap conductance has been validated by using experimental results. In the validation, the behaviors of fuel temperature and off-center temperature are selected as the major parameters
Energy Technology Data Exchange (ETDEWEB)
Hermanne, A., E-mail: aherman@vub.ac.be [Cyclotron Laboratory, Vrije Universiteit Brussel, Brussel 1090 (Belgium); Adam-Rebeles, R. [Cyclotron Laboratory, Vrije Universiteit Brussel, Brussel 1090 (Belgium); Tarkanyi, F.; Takacs, S.; Csikai, J. [Institute for Nuclear Research, Hungarian Academy of Sciences, 4026 Debrecen (Hungary); Takacs, M.P. [Institute of Physics, University of Debrecen, 4026 Debrecen (Hungary); Ignatyuk, A. [Institute of Physics and Power Engineering, Obninsk 246020 (Russian Federation)
2013-09-15
Activation products of rare earth elements are gaining importance in medical and technical applications. In stacked foil irradiations, followed by high resolution gamma spectroscopy, the cross-sections for production of {sup 161,165}Er, {sup 166g}Ho on {sup 165}Ho and {sup 135,137m,137g,139}Ce, {sup 140}La, {sup 133m,133g,cum}Ba and {sup 136}Cs on {sup nat}La targets were measured up to 50 MeV. Reduced uncertainty is obtained by simultaneous remeasurement of the {sup 27}Al(d,x){sup 24,22}Na monitor reactions over the whole energy range. A comparison with experimental literature values and results from updated theoretical codes (ALICE-D, EMPIRE-D and the TENDL2012 online library) is discussed.
Experimental verification of the linear and non-linear versions of a panel code
Grigoropoulos, G. J.; Katsikis, C.; Chalkias, D. S.
2011-03-01
In the proposed paper numerical calculations are carried out using two versions of a three-dimensional, timedomain panel method developed by the group of Prof. P. Sclavounos at MIT, i.e. the linear code SWAN2, enabling optionally the use of the instantaneous non-linear Froude-Krylov and hydrostatic forces and the fully non-linear SWAN4. The analytical results are compared with experimental results for three hull forms with increasing geometrical complexity, the Series 60, a reefer vessel with stern bulb and a modern fast ROPAX hull form with hollow bottom in the stern region. The details of the geometrical modeling of the hull forms are discussed. In addition, since SWAN4 does not support transom sterns, only the two versions of SWAN2 were evaluated over experimental results for the parent hull form of the NTUA double-chine, wide-transom, high-speed monohull series. The effect of speed on the numerical predictions was investigated. It is concluded that both versions of SWAN2 the linear and the one with the non-linear Froude-Krylov and hydrostatic forces provide a more robust tool for prediction of the dynamic response of the vessels than the non-linear SWAN4 code. In general, their results are close to what was expected on the basis of experience. Furthermore, the use of the option of non-linear Froude-Krylov and hydrostatic forces is beneficial for the accuracy of the predictions. The content of the paper is based on the Diploma thesis of the second author, supervised by the first one and further refined by the third one.
Directory of Open Access Journals (Sweden)
Smith Richard D
2011-08-01
Full Text Available Abstract Background Complete and accurate genome annotation is crucial for comprehensive and systematic studies of biological systems. However, determining protein-coding genes for most new genomes is almost completely performed by inference using computational predictions with significant documented error rates (> 15%. Furthermore, gene prediction programs provide no information on biologically important post-translational processing events critical for protein function. Results We experimentally annotated the bacterial pathogen Salmonella Typhimurium 14028, using "shotgun" proteomics to accurately uncover the translational landscape and post-translational features. The data provide protein-level experimental validation for approximately half of the predicted protein-coding genes in Salmonella and suggest revisions to several genes that appear to have incorrectly assigned translational start sites, including a potential novel alternate start codon. Additionally, we uncovered 12 non-annotated genes missed by gene prediction programs, as well as evidence suggesting a role for one of these novel ORFs in Salmonella pathogenesis. We also characterized post-translational features in the Salmonella genome, including chemical modifications and proteolytic cleavages. We find that bacteria have a much larger and more complex repertoire of chemical modifications than previously thought including several novel modifications. Our in vivo proteolysis data identified more than 130 signal peptide and N-terminal methionine cleavage events critical for protein function. Conclusion This work highlights several ways in which application of proteomics data can improve the quality of genome annotations to facilitate novel biological insights and provides a comprehensive proteome map of Salmonella as a resource for systems analysis.
Experimental verification of the linear and non-linear versions of a panel code
Directory of Open Access Journals (Sweden)
G.J. Grigoropoulos
2011-03-01
Full Text Available In the proposed paper numerical calculations are carried out using two versions of a three-dimensional, time-domain panel method developed by the group of Prof. P. Sclavounos at MIT, i.e. the linear code SWAN2, enabling optionally the use of the instantaneous non-linear Froude-Krylov and hydrostatic forces and the fully non-linear SWAN4. The analytical results are compared with experimental results for three hull forms with increasing geometrical complexity, the Series 60, a reefer vessel with stern bulb and a modern fast ROPAX hull form with hollow bottom in the stern region. The details of the geometrical modeling of the hull forms are discussed. In addition, since SWAN4 does not support transom sterns, only the two versions of SWAN2 were evaluated over experimental results for the parent hull form of the NTUA double-chine, wide-transom, high-speed monohull series. The effect of speed on the numerical predictions was investigated. It is concluded that both versions of SWAN2 the linear and the one with the non-linear Froude-Krylov and hydrostatic forces provide a more robust tool for prediction of the dynamic response of the vessels than the non-linear SWAN4 code. In general, their results are close to what was expected on the basis of experience. Furthermore, the use of the option of non-linear Froude-Krylov and hydrostatic forces is beneficial for the accuracy of the predictions. The content of the paper is based on the Diploma thesis of the second author, supervised by the first one and further refined by the third one.
Energy Technology Data Exchange (ETDEWEB)
S.T. Revankar; W. Zhou; Gavin Henderson
2008-07-08
The main goal of the project was to study analytically and experimentally the condensation heat transfer for the passive condenser system such as GE Economic Simplified Boiling Water Reactor (ESBWR). The effect of noncondensable gas in condenser tube and the reduction of secondary pool water level to the condensation heat transfer coefficient was the main focus in this research. The objectives of this research were to : 1) obtain experimental data on the local and tube averaged condensation heat transfer rates for the PCCS with non-condensable and with change in the secondary pool water, 2) assess the RELAP5 and TRACE computer code against the experimental data, and 3) develop mathematical model and ehat transfer correlation for the condensation phenomena for system code application. The project involves experimentation, theoretical model development and verification, and thermal- hydraulic codes assessment.
Experimental verification of the feasibility of a quantum channel between space and Earth
Energy Technology Data Exchange (ETDEWEB)
Villoresi, P; Bonato, C [Department of Information Engineering, University of Padova and INFM-CNR LUXOR Laboratory for Ultraviolet and X-ray Optical Research, Padova (Italy); Jennewein, T; Aspelmeyer, M; Zeilinger, A [Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Vienna (Austria); Tamburini, F; Barbieri, C [Department of Astronomy, University of Padova (Italy); Ursin, R [Faculty of Physics, Institute for Experimental Physics, University of Vienna (Austria); Pernechele, C [INAF-Cagliari, Capoterra (Canada) (Italy); Luceri, V [Centro di Geodesia Spaziale ' G Colombo' , e-GEOS SpA, Matera (Italy); Bianco, G [Centro di Geodesia Spaziale ' G Colombo' , Agenzia Spaziale Italiana, Matera (Italy)], E-mail: paolo.villoresi@unipd.it
2008-03-15
Extending quantum communication to space environments would enable us to perform fundamental experiments on quantum physics as well as applications of quantum information at planetary and interplanetary scales. Here, we report on the first experimental study of the conditions for the implementation of the single-photon exchange between a satellite and an Earth-based station. We built an experiment that mimics a single photon source on a satellite, exploiting the telescope at the Matera Laser Ranging Observatory of the Italian Space Agency to detect the transmitted photons. Weak laser pulses, emitted by the ground-based station, are directed toward a satellite equipped with cube-corner retroreflectors. These reflect a small portion of the pulse, with an average of less-than-one photon per pulse directed to our receiver, as required for faint-pulse quantum communication. We were able to detect returns from satellite Ajisai, a low-Earth orbit geodetic satellite, whose orbit has a perigee height of 1485 km.
Experimental estimation of average fidelity of a Clifford gate on a 7-qubit quantum processor.
Lu, Dawei; Li, Hang; Trottier, Denis-Alexandre; Li, Jun; Brodutch, Aharon; Krismanich, Anthony P; Ghavami, Ahmad; Dmitrienko, Gary I; Long, Guilu; Baugh, Jonathan; Laflamme, Raymond
2015-04-10
One of the major experimental achievements in the past decades is the ability to control quantum systems to high levels of precision. To quantify the level of control we need to characterize the dynamical evolution. Full characterization via quantum process tomography is impractical and often unnecessary. For most practical purposes, it is enough to estimate more general quantities such as the average fidelity. Here we use a unitary 2-design and twirling protocol for efficiently estimating the average fidelity of Clifford gates, to certify a 7-qubit entangling gate in a nuclear magnetic resonance quantum processor. Compared with more than 10^{8} experiments required by full process tomography, we conducted 1656 experiments to satisfy a statistical confidence level of 99%. The average fidelity of this Clifford gate in experiment is 55.1%, and rises to at least 87.5% if the signal's decay due to decoherence is taken into account. The entire protocol of certifying Clifford gates is efficient and scalable, and can easily be extended to any general quantum information processor with minor modifications.
Experimental investigations of synchrotron radiation at the onset of the quantum regime
Andersen, Kristoffer K; Knudsen, H; Thomsen, H D; Uggerhøj, U I; Sona, P; Mangiarotti, A; Ketel, T J; Dizdar, A; Ballestrero, S
2012-01-01
The classical description of synchrotron radiation fails at large Lorentz factors, $\\gamma$, for relativistic electrons crossing strong transverse magnetic fields $B$. In the rest frame of the electron this field is comparable to the so-called critical field $B_0 = 4.414\\cdot10^9$ T. For $\\chi = \\gamma B/B_0 \\simeq 1$ quantum corrections are essential for the description of synchrotron radiation to conserve energy. With electrons of energies 10-150 GeV penetrating a germanium single crystal along the $$ axis, we have experimentally investigated the transition from the regime where classical synchrotron radiation is an adequate description, to the regime where the emission drastically changes character; not only in magnitude, but also in spectral shape. The spectrum can only be described by quantum synchrotron radiation formulas. Apart from being a test of strong-field quantum electrodynamics, the experimental results are also relevant for the design of future linear colliders where beamstrahlung - a closely r...
A selection of experimental test cases for the validation of CFD codes, volume 1
1994-08-01
This report presents the results of a study by Working Group 14 of the AGARD Fluid Dynamics Panel. This group was formed to establish an accessible, detailed experimental data base for the validation of Computational Fluid Dynamics (CFD) codes. The thirty nine test cases that are documented cover the subsonic, transonic, and supersonic flow regimes and five classes of geometries. Included in the five classes of geometries are: two dimensional airfoils; three dimensional wings, designed for predominantly attached flow conditions; slender bodies, typical of missile type configurations; delta wings, characterized by a conical type of vortex flow; and complex configurations, either in a geometrical sense or because of complicated flow interactions. The report is presented in two volumes. Volume 1 provides a review of the theoretical and experimental requirements, a general introduction and summary of the test cases, and recommendations for the future. Volume 2 contains detailed information on the test cases. The relevant data of all test cases has been compiled on floppy disks, which can be obtained through National Centers.
Experimental investigations of synchrotron radiation at the onset of the quantum regime
DEFF Research Database (Denmark)
Andersen, Kristoffer; Uggerhøj, Ulrik Ingerslev
the magnetic field is comparable to the critical field, quantum corrections are essential for the description of synchrotron radiation to conserve energy. With electrons of energies 10-150 GeV penetrating a germanium single crystal along the axis, we have experimentally investigated the transition from......The classical description of synchrotron radiation fails at large Lorentz factors for relativistic electrons crossing strong transverse magnetic fields. In the rest frame of the electron this field is comparable to the so-called critical field of 4.414*109 T. When the Lorentz factor times...... the regime where classical synchrotron radiation is an adequate description, to the regime where the emission drastically changes character; not only in magnitude, but also in spectral shape. The spectrum can only be described by quantum synchrotron radiation formulas. Apart from being a test of strong...
Experimental investigations of synchrotron radiation at the onset of the quantum regime
DEFF Research Database (Denmark)
Andersen, Kristoffer; Knudsen, Helge; Uggerhøj, Ulrik Ingerslev
2012-01-01
= \\gamma B/B_0 \\simeq 1$ quantum corrections are essential for the description of synchrotron radiation to conserve energy. With electrons of energies 10-150 GeV penetrating a germanium single crystal along the $\\langle110\\rangle$ axis, we have experimentally investigated the transition from the regime......The classical description of synchrotron radiation fails at large Lorentz factors, $\\gamma$, for relativistic electrons crossing strong transverse magnetic fields $B$. In the rest frame of the electron this field is comparable to the so-called critical field $B_0 = 4.414\\cdot10^9$ T. For $\\chi...... where classical synchrotron radiation is an adequate description, to the regime where the emission drastically changes character; not only in magnitude, but also in spectral shape. The spectrum can only be described by quantum synchrotron radiation formulas. Apart from being a test of strong...
Experimental demonstration of a fully inseparable quantum state with nonlocalizable entanglement.
Mičuda, M; Koutný, D; Miková, M; Straka, I; Ježek, M; Mišta, L
2017-03-27
Localizability of entanglement in fully inseparable states is a key ingredient of assisted quantum information protocols as well as measurement-based models of quantum computing. We investigate the existence of fully inseparable states with nonlocalizable entanglement, that is, with entanglement which cannot be localized between any pair of subsystems by any measurement on the remaining part of the system. It is shown, that the nonlocalizable entanglement occurs already in suitable mixtures of a three-qubit GHZ state and white noise. Further, we generalize this set of states to a two-parametric family of fully inseparable three-qubit states with nonlocalizable entanglement. Finally, we demonstrate experimentally the existence of nonlocalizable entanglement by preparing and characterizing one state from the family using correlated single photons and linear optical circuit.
Energy Technology Data Exchange (ETDEWEB)
Kalimullah, M. [Argonne National Lab. (ANL), Argonne, IL (United States); Olson, Arne P. [Argonne National Lab. (ANL), Argonne, IL (United States); Feldman, E. E. [Argonne National Lab. (ANL), Argonne, IL (United States); Hanan, N. [Argonne National Lab. (ANL), Argonne, IL (United States); Dionne, B. [Argonne National Lab. (ANL), Argonne, IL (United States)
2015-04-07
The document compiles in a single volume several verification and validation works done for the PLTEMP/ANL code during the years of its development and improvement. Some works that are available in the open literature are simply referenced at the outset, and are not included in the document. PLTEMP has been used in conversion safety analysis reports of several US and foreign research reactors that have been licensed and converted. A list of such reactors is given. Each chapter of the document deals with the verification or validation of a specific model. The model verification is usually done by comparing the code with hand calculation, Microsoft spreadsheet calculation, or Mathematica calculation. The model validation is done by comparing the code with experimental data or a more validated code like the RELAP5 code.
Collins, Robert J; Amiri, Ryan; Fujiwara, Mikio; Honjo, Toshimori; Shimizu, Kaoru; Tamaki, Kiyoshi; Takeoka, Masahiro; Sasaki, Masahide; Andersson, Erika; Buller, Gerald S
2017-06-12
Ensuring the integrity and transferability of digital messages is an important challenge in modern communications. Although purely mathematical approaches exist, they usually rely on the computational complexity of certain functions, in which case there is no guarantee of long-term security. Alternatively, quantum digital signatures offer security guaranteed by the physical laws of quantum mechanics. Prior experimental demonstrations of quantum digital signatures in optical fiber have typically been limited to operation over short distances and/or operated in a laboratory environment. Here we report the experimental transmission of quantum digital signatures over channel losses of up to 42.8 ± 1.2 dB in a link comprised of 90 km of installed fiber with additional optical attenuation introduced to simulate longer distances. The channel loss of 42.8 ± 1.2 dB corresponds to an equivalent distance of 134.2 ± 3.8 km and this represents the longest effective distance and highest channel loss that quantum digital signatures have been shown to operate over to date. Our theoretical model indicates that this represents close to the maximum possible channel attenuation for this quantum digital signature protocol, defined as the loss for which the signal rate is comparable to the dark count rate of the detectors.
Directory of Open Access Journals (Sweden)
C. Eichler
2015-12-01
Full Text Available Improving the understanding of strongly correlated quantum many-body systems such as gases of interacting atoms or electrons is one of the most important challenges in modern condensed matter physics, materials research, and chemistry. Enormous progress has been made in the past decades in developing both classical and quantum approaches to calculate, simulate, and experimentally probe the properties of such systems. In this work, we use a combination of classical and quantum methods to experimentally explore the properties of an interacting quantum gas by creating experimental realizations of continuous matrix product states—a class of states that has proven extremely powerful as a variational ansatz for numerical simulations. By systematically preparing and probing these states using a circuit quantum electrodynamics system, we experimentally determine a good approximation to the ground-state wave function of the Lieb-Liniger Hamiltonian, which describes an interacting Bose gas in one dimension. Since the simulated Hamiltonian is encoded in the measurement observable rather than the controlled quantum system, this approach has the potential to apply to a variety of models including those involving multicomponent interacting fields. Our findings also hint at the possibility of experimentally exploring general properties of matrix product states and entanglement theory. The scheme presented here is applicable to a broad range of systems exploiting strong and tunable light-matter interactions.
Zarei, Mohammad Hossein
2017-10-01
Graphs and recently hypergraphs have been known as an important tool for considering different properties of quantum many-body systems. In this paper, we study a mapping between an important class of quantum systems, namely quantum Calderbank-Shor-Steane (CSS) codes, and Ising-like systems by using hypergraphs. We show that the Hamiltonian corresponding to a CSS code on a hypergraph H which is perturbed by a uniform magnetic field is mapped to Hamiltonian of a Ising-like system on dual hypergraph H ˜ in a transverse field. Interestingly, we show that a strong regime of couplings in one of the systems is mapped to a weak regime of couplings in another one. We also give some applications for such a mapping where we study robustness of different topological CSS codes against a uniform magnetic field including Kitaev's toric codes defined on graphs and color codes in different dimensions. We show that a perturbed Kitaev's toric code on an arbitrary graph is mapped to an Ising model in a transverse field on the same graph and a perturbed color code on a D colex is mapped to a Ising-like model on a D -simplicial lattice in a transverse field. In particular, we use these results to explicitly compare the robustness of toric codes to uniform magnetic-field perturbations on different graphs. Interestingly, our results show that the robustness of such topological codes defined on graphs decreases with increasing dimension. Furthermore, we also use the duality mapping for some self-dual models where we exactly derive the point of phase transition.
Al-Khalili, Jim
2003-01-01
In this lively look at quantum science, a physicist takes you on an entertaining and enlightening journey through the basics of subatomic physics. Along the way, he examines the paradox of quantum mechanics--beautifully mathematical in theory but confoundingly unpredictable in the real world. Marvel at the Dual Slit experiment as a tiny atom passes through two separate openings at the same time. Ponder the peculiar communication of quantum particles, which can remain in touch no matter how far apart. Join the genius jewel thief as he carries out a quantum measurement on a diamond without ever touching the object in question. Baffle yourself with the bizzareness of quantum tunneling, the equivalent of traveling partway up a hill, only to disappear then reappear traveling down the opposite side. With its clean, colorful layout and conversational tone, this text will hook you into the conundrum that is quantum mechanics.
La Cour, Brian R.
2017-07-01
An experiment has recently been performed to demonstrate quantum nonlocality by establishing contextuality in one of a pair of photons encoding four qubits; however, low detection efficiencies and use of the fair-sampling hypothesis leave these results open to possible criticism due to the detection loophole. In this Letter, a physically motivated local hidden-variable model is considered as a possible mechanism for explaining the experimentally observed results. The model, though not intrinsically contextual, acquires this quality upon post-selection of coincident detections.
DEFF Research Database (Denmark)
Poel, Mike van der; Gehrig, Edeltraud; Hess, Ortwin
2005-01-01
Ultrafast gain dynamics in an optical amplifier with an active layer of self-organized quantum dots (QDs) emitting near 1.3$muhbox m$is characterized experimentally in a pump-probe experiment and modeled theoretically on the basis of QD Maxwell–Bloch equations. Experiment and theory are in good...... agreement and show ultrafast subpicoseconds gain recovery followed by a slower 5 ps recovery. This behavior is found to be mainly caused by longitudinal optical phonon scattering and strongly dependents on electronic structure and confinement energy of the dots. A low amplitude-phase coupling ($alpha$factor...
Máttar, A.; Skrzypczyk, P.; Aguilar, G. H.; Nery, R. V.; Souto Ribeiro, P. H.; Walborn, S. P.; Cavalcanti, D.
2017-03-01
Recently, Cavalcanti et al (2015) proposed a method to certify the presence of entanglement in asymmetric networks, where some users do not have control over the measurements they are performing. Such asymmetry naturally emerges in realistic situations, such as in cryptographic protocols over quantum networks. Here we implement such ‘semi-device-independent’ techniques to experimentally witness all types of entanglement on a three-qubit photonic W state. Furthermore, we analyse the amount of genuine randomness that can be certified in this scenario from any bipartition of the three-qubit W state.
Teles, João; Rivera-Ascona, Christian; Polli, Roberson S.; Oliveira-Silva, Rodrigo; Vidoto, Edson L. G.; Andreeta, José P.; Bonagamba, Tito J.
2015-06-01
Nuclear magnetic resonance (NMR) has been widely used in the context of quantum information processing (QIP). However, despite the great similarities between NMR and nuclear quadrupole resonance (NQR), no experimental implementation for QIP using NQR has been reported. We describe the implementation of basic quantum gates and their applications on the creation and manipulation of pseudopure states using linearly polarized radiofrequency pulses under static magnetic field perturbation. The NQR quantum operations were implemented using a single-crystal sample of and observing nuclei, which possess spin 3/2 and give rise to a two-qubit system. The results are very promising and indicate that NQR can be successfully used for performing fundamental experiments in QIP. One advantage of NQR in comparison with NMR is that the main interaction is internal to the sample, which makes the system more compact, lowering its cost and making it easier to be miniaturized to solid-state devices. Furthermore, as an example, the study of squeezed spin states could receive relevant contributions from NQR.
Overview of experimental results and code validation activities at Alcator C-Mod
Greenwald, M.; Bader, A.; Baek, S.; Barnard, H.; Beck, W.; Bergerson, W.; Bespamyatnov, I.; Bitter, M.; Bonoli, P.; Brookman, M.; Brower, D.; Brunner, D.; Burke, W.; Candy, J.; Chilenski, M.; Chung, M.; Churchill, M.; Cziegler, I.; Davis, E.; Dekow, G.; Delgado-Aparicio, L.; Diallo, A.; Ding, W.; Dominguez, A.; Ellis, R.; Ennever, P.; Ernst, D.; Faust, I.; Fiore, C.; Fitzgerald, E.; Fredian, T.; Garcia, O. E.; Gao, C.; Garrett, M.; Golfinopoulos, T.; Granetz, R.; Groebner, R.; Harrison, S.; Harvey, R.; Hartwig, Z.; Hill, K.; Hillairet, J.; Howard, N.; Hubbard, A. E.; Hughes, J. W.; Hutchinson, I.; Irby, J.; James, A. N.; Kanojia, A.; Kasten, C.; Kesner, J.; Kessel, C.; Kube, R.; LaBombard, B.; Lau, C.; Lee, J.; Liao, K.; Lin, Y.; Lipschultz, B.; Ma, Y.; Marmar, E.; McGibbon, P.; Meneghini, O.; Mikkelsen, D.; Miller, D.; Mumgaard, R.; Murray, R.; Ochoukov, R.; Olynyk, G.; Pace, D.; Park, S.; Parker, R.; Podpaly, Y.; Porkolab, M.; Preynas, M.; Pusztai, I.; Reinke, M.; Rice, J.; Rowan, W.; Scott, S.; Shiraiwa, S.; Sierchio, J.; Snyder, P.; Sorbom, B.; Soukhanovskii, V.; Stillerman, J.; Sugiyama, L.; Sung, C.; Terry, D.; Terry, J.; Theiler, C.; Tsujii, N.; Vieira, R.; Walk, J.; Wallace, G.; White, A.; Whyte, D.; Wilson, J.; Wolfe, S.; Woller, K.; Wright, G.; Wright, J.; Wukitch, S.; Wurden, G.; Xu, P.; Yang, C.; Zweben, S.
2013-10-01
Recent research on the Alcator C-Mod tokamak has focused on a range of scientific issues with particular emphasis on ITER needs and on detailed comparisons between experimental measurements and predictive models. Research on ICRF (ion cyclotron range of frequencies) heating emphasized the origins and mitigation of metallic impurities while work on lower hybrid current drive experiments have focused on linear and nonlinear wave interactions that limit efficiency at high densities in regimes with low single pass absorption. Experiments in core turbulence and transport focused on quantitative, multi-field comparisons between nonlinear gyro-kinetics simulations and experimental measurements of profiles, fluxes and fluctuations. Experiments into self-generated rotation observed spontaneous flow reversal at a critical density identical to the transition density between linear ohmic confinement and saturated ohmic confinement regimes. H-mode studies have measured pedestal widths consistent with kinetic-ballooning-mode-like instabilities, while the pedestal heights quantitatively match the EPED code predictions. Experiments with I-mode have increased the operating window for this promising edge-localized-mode-free regime. Extrapolation of I-mode to ITER suggests that the fusion gain Q ∼ 10 could be possible in ITER. Investigations into the physics and scaling of the power exhaust channel width in attached enhanced D-alpha H-mode and L-mode plasma showed a direct connection between the midplane pressure-folding length and the outer divertor target footprint. The width was found to scale inversely with IP, while being independent of conducted power, BT or q95 and insensitive to the scrape-off layer connection length—a behaviour that suggests critical-gradient physics sets both pressure and heat-flux profiles.
Experimental Test of the “Special State” Theory of Quantum Measurement
Directory of Open Access Journals (Sweden)
Lawrence S. Schulman
2012-04-01
Full Text Available An experimental test of the “special state” theory of quantum measurement is proposed. It should be feasible with present-day laboratory equipment and involves a slightly elaborated Stern–Gerlach setup. The “special state” theory is conservative with respect to quantum mechanics, but radical with respect to statistical mechanics, in particular regarding the arrow of time. In this article background material is given on both quantum measurement and statistical mechanics aspects. For example, it is shown that future boundary conditions would not contradict experience, indicating that the fundamental equal-a-priori-probability assumption at the foundations of statistical mechanics is far too strong (since future conditioning reduces the class of allowed states. The test is based on a feature of this theory that was found necessary in order to recover standard (Born probabilities in quantum measurements. Specifically, certain systems should have “noise” whose amplitude follows the long-tailed Cauchy distribution. This distribution is marked by the occasional occurrence of extremely large signals as well as a non-self-averaging property. The proposed test is a variant of the Stern–Gerlach experiment in which protocols are devised, some of which will require the presence of this noise, some of which will not. The likely observational schemes would involve the distinction between detection and non-detection of that “noise”. The signal to be detected (or not would be either single photons or electric fields (and related excitations in the neighborhood of the ends of the magnets.
He, Jing; Wen, Xuejie; Chen, Ming; Chen, Lin; Su, Jinshu
2015-01-01
To improve the transmission performance of multiband orthogonal frequency division multiplexing (MB-OFDM) ultra-wideband (UWB) over optical fiber, a pre-coding scheme based on low-density parity-check (LDPC) is adopted and experimentally demonstrated in the intensity-modulation and direct-detection MB-OFDM UWB over fiber system. Meanwhile, a symbol synchronization and pilot-aided channel estimation scheme is implemented on the receiver of the MB-OFDM UWB over fiber system. The experimental results show that the LDPC pre-coding scheme can work effectively in the MB-OFDM UWB over fiber system. After 70 km standard single-mode fiber (SSMF) transmission, at the bit error rate of 1 × 10-3, the receiver sensitivities are improved about 4 dB when the LDPC code rate is 75%.
Quantum Hall resistance standard in graphene devices under relaxed experimental conditions
Ribeiro-Palau, R.; Lafont, F.; Brun-Picard, J.; Kazazis, D.; Michon, A.; Cheynis, F.; Couturaud, O.; Consejo, C.; Jouault, B.; Poirier, W.; Schopfer, F.
2015-11-01
The quantum Hall effect provides a universal standard for electrical resistance that is theoretically based on only the Planck constant h and the electron charge e. Currently, this standard is implemented in GaAs/AlGaAs, but graphene's electronic properties have given hope for a more practical device. Here, we demonstrate that the experimental conditions necessary for the operation of devices made of high-quality graphene grown by chemical vapour deposition on silicon carbide can be extended and significantly relaxed compared with those for state-of-the-art GaAs/AlGaAs devices. In particular, the Hall resistance can be accurately quantized to within 1 × 10-9 over a 10 T wide range of magnetic flux density, down to 3.5 T, at a temperature of up to 10 K or with a current of up to 0.5 mA. This experimental simplification highlights the great potential of graphene in the development of user-friendly and versatile quantum standards that are compatible with broader industrial uses beyond those in national metrology institutes. Furthermore, the measured agreement of the quantized Hall resistance in graphene and GaAs/AlGaAs, with an ultimate uncertainty of 8.2 × 10-11, supports the universality of the quantum Hall effect. This also provides evidence of the relation of the quantized Hall resistance with h and e, which is crucial for the new Système International d'unités to be based on fixing such fundamental constants of nature.
Curceanu, C; Bragadireanu, M; Pietreanu, T; Sperandio, L; Marton, J; Sirghi, D L; Widmann, E; Ishiwatari, T; Zmeskal, J; Ponta, T; Laubenstein, M; Cargnelli, M; Milotti, E; Bartalucci, S; Iliescu, M; Guaraldo, C; Doce, O V; Bertolucci, S; Egger, J P; Vidal, A R; Sirghi, F; Di Matteo, S
2011-01-01
The Pauli exclusion principle (PEP) is one of the basic principles of modern physics. Being at the very basis of our understanding of matter, as many other fundamental principles it spurs, presently, a lively debate on its possible limits, deeply rooted in the very foundations of Quantum Field Theory. Therefore, it is extremely important to test the limits of its validity. Quon theory provides a suitable mathematical framework of possible violation of PEP, where the violation parameter q translates into a probability of violating PEP. Experimentally, setting a bound on PEP violation means confining the violation parameter to a value very close to either 1 (for bosons) or -1 (for fermions). The VIP (VIolation of the Pauli exclusion principle) experiment established a limit on the probability that PEP is violated by electrons, using the method of searching for PEP forbidden atomic transitions in copper. We describe the experimental method, the obtained results, both in terms of the q-parameter from quon theory ...
Towards optimal experimental tests on the reality of the quantum state
Knee, George C.
2017-02-01
The Barrett-Cavalcanti-Lal-Maroney (BCLM) argument stands as the most effective means of demonstrating the reality of the quantum state. Its advantages include being derived from very few assumptions, and a robustness to experimental error. Finding the best way to implement the argument experimentally is an open problem, however, and involves cleverly choosing sets of states and measurements. I show that techniques from convex optimisation theory can be leveraged to numerically search for these sets, which then form a recipe for experiments that allow for the strongest statements about the ontology of the wavefunction to be made. The optimisation approach presented is versatile, efficient and can take account of the finite errors present in any real experiment. I find significantly improved low-cardinality sets which are guaranteed partially optimal for a BCLM test in low Hilbert space dimension. I further show that mixed states can be more optimal than pure states.
Energy Technology Data Exchange (ETDEWEB)
Nagels-Silvert, V
2004-09-15
The main purpose of this thesis is to get experimental data for the testing and validation of atomic physics codes dealing with non-local-thermodynamical-equilibrium plasmas. The first part is dedicated to the spectroscopic study of xenon and krypton plasmas that have been produced by a nanosecond laser pulse interacting with a gas jet. A Thomson scattering diagnostic has allowed us to measure independently plasma parameters such as electron temperature, electron density and the average ionisation state. We have obtained time integrated spectra in the range between 5 and 10 angstroms. We have identified about one hundred xenon rays between 8.6 and 9.6 angstroms via the use of the Relac code. We have discovered unknown rays for the krypton between 5.2 and 7.5 angstroms. In a second experiment we have extended the wavelength range to the X UV domain. The Averroes/Transpec code has been tested in the ranges from 9 to 15 angstroms and from 10 to 130 angstroms, the first range has been well reproduced while the second range requires a more complex data analysis. The second part is dedicated to the spectroscopic study of aluminium, selenium and samarium plasmas in femtosecond operating rate. We have designed an interferometry diagnostic in the frequency domain that has allowed us to measure the expanding speed of the target's backside. Via the use of an adequate isothermal model this parameter has led us to know the plasma electron temperature. Spectra and emission times of various rays from the aluminium and selenium plasmas have been computed satisfactorily with the Averroes/Transpec code coupled with Film and Multif hydrodynamical codes. (A.C.)
Energy Technology Data Exchange (ETDEWEB)
Pesetti, A., E-mail: alessio.pesetti@for.unipi.it [University of Pisa, DICI, 56122 Pisa, PI (Italy); Del Nevo, A. [ENEA, C.R. Brasimone, 40032 Camugnano, BO (Italy); Forgione, N. [University of Pisa, DICI, 56122 Pisa, PI (Italy)
2015-08-15
Highlights: • In the framework of THINS Project, four experimental tests were performed investigating water–LBE interaction in LIFUS5/Mod2 facility at ENEA RC Brasimone. • High quality data were acquired to improve the phenomena understanding and support codes development/validation. • Post-test activity by SIMMER III code was performed by a simplified model. • The obtained numerical results are qualitatively in agreement with the experimental data. - Abstract: In the frame of the THINS Project, an experimental campaign was performed on LIFUS5/Mod2 facility at ENEA RC Brasimone, aiming to investigate the water–LBE interaction. Such a phenomenon occurs as consequence of a postulated Steam Generator Tube Rupture event in a HLMFR system. Four tests were performed injecting sub-cooled water at 40 bar into a reaction vessel partially filled by low pressure LBE at 400 °C. The post-test activity was performed by the SIMMER-III code in order to improve the understanding of the involved phenomena and to confirm the code capabilities in simulating the water–LBE interaction. The calculated data showed a qualitatively agreement with the measured values and a faster reaction kinetics due to the modelling assumptions.
Collins, Robert J; Amiri, Ryan; Fujiwara, Mikio; Honjo, Toshimori; Shimizu, Kaoru; Tamaki, Kiyoshi; Takeoka, Masahiro; Andersson, Erika; Buller, Gerald S; Sasaki, Masahide
2016-11-01
Quantum digital signatures (QDSs) apply quantum mechanics to the problem of guaranteeing message integrity and non-repudiation with information-theoretical security, which are complementary to the confidentiality realized by quantum key distribution (QKD). Previous experimental demonstrations have been limited to transmission distances of less than 5 km of optical fiber in a laboratory setting. Here we report, to the best of our knowledge, the first demonstration of QDSs over installed optical fiber, as well as the longest transmission link reported to date. This demonstration used a 90 km long differential phase shift QKD to achieve approximately one signed bit per second, an increase in the signature generation rate of several orders of magnitude over previous optical fiber demonstrations.
Nguyen, Quynh Nhu Ngoc
The results of quantum chemical calculations reveal that polyanionic gallium-based cages accelerate cyclization reactions of pentadienyl alcohols by significantly increasing basicity of the substrate hydroxyl group. The energy barrier for cyclization of the pentadienyl cation after water loss is already low in the background reaction and is altered fairly little by the cage. The calculations for other non-alcohol substrates also suggest that the cage increases the basicity of amine and phosphine groups, though to a lesser extend comparing to the alcohol substrate. Due to their twisting patterns, alpha-helical peptides are known to have overall "macrodipoles" along the principal axes as the result of the backbone carbonyl groups pointing toward the C-terminus. As the dipoles have implications in helical bundles, interactions with lipid bilayers, and distribution of charge, chemists have long been interested in employing the macrodipole in modifications of peptides' catalytic activities. In this studied, we examined the impact of both global and local noncovalent interactions between peptide catalysts and substrates in the first transesterification step, in hope of designing a better peptide catalysts to aid in ester metabolism. Quantum mechanical calculations helped predict whether the targeted medium-sized cyclic peptide products would more likely be the major products, before the experimental team invested extensive resources and time to carry out the syntheses. Many systems were found to favor the medium-sized cyclic peptides, whereas one system was predicted to result in polycyclic product, and the latter experimental observations agreed with these predictions. Naturally occurring cyclic peptides display various biological activities due to their diverse structures. Understanding the dominant structures of these peptides could help give insight into protein-protein interactions or substrate-protein binding. With the experimental NMR data obtained for the
Lobanov, P. D.; Usov, E. V.; Butov, A. A.; Pribaturin, N. A.; Mosunova, N. A.; Strizhov, V. F.; Chukhno, V. I.; Kutlimetov, A. E.
2017-10-01
Experiments with impulse gas injection into model coolants, such as water or the Rose alloy, performed at the Novosibirsk Branch of the Nuclear Safety Institute, Russian Academy of Sciences, are described. The test facility and the experimental conditions are presented in details. The dependence of coolant pressure on the injected gas flow and the time of injection was determined. The purpose of these experiments was to verify the physical models of thermohydraulic codes for calculation of the processes that could occur during the rupture of tubes of a steam generator with heavy liquid metal coolant or during fuel rod failure in water-cooled reactors. The experimental results were used for verification of the HYDRA-IBRAE/LM system thermohydraulic code developed at the Nuclear Safety Institute, Russian Academy of Sciences. The models of gas bubble transportation in a vertical channel that are used in the code are described in detail. A two-phase flow pattern diagram and correlations for prediction of friction of bubbles and slugs as they float up in a vertical channel and of two-phase flow friction factor are presented. Based on the results of simulation of these experiments using the HYDRA-IBRAE/LM code, the arithmetic mean error in predicted pressures was calculated, and the predictions were analyzed considering the uncertainty in the input data, geometry of the test facility, and the error of the empirical correlation. The analysis revealed major factors having a considerable effect on the predictions. The recommendations are given on updating of the experimental results and improvement of the models used in the thermohydraulic code.
Experimental study of non-binary LDPC coding for long-haul coherent optical QPSK transmissions.
Zhang, Shaoliang; Arabaci, Murat; Yaman, Fatih; Djordjevic, Ivan B; Xu, Lei; Wang, Ting; Inada, Yoshihisa; Ogata, Takaaki; Aoki, Yasuhiro
2011-09-26
The performance of rate-0.8 4-ary LDPC code has been studied in a 50 GHz-spaced 40 Gb/s DWDM system with PDM-QPSK modulation. The net effective coding gain of 10 dB is obtained at BER of 10(-6). With the aid of time-interleaving polarization multiplexing and MAP detection, 10,560 km transmission over legacy dispersion managed fiber is achieved without any countable errors. The proposed nonbinary quasi-cyclic LDPC code achieves an uncoded BER threshold at 4×10(-2). Potential issues like phase ambiguity and coding length are also discussed when implementing LDPC in current coherent optical systems. © 2011 Optical Society of America
Theoretical studies for experimental implementation of quantum computing with trapped ions
Yoshimura, Bryce T.
Certain quantum many-body physics problems, such as the transverse field Ising model are intractable on a classical computer, meaning that as the number of particles grows, or spins, the amount of memory and computational time required to solve the problem exactly increases faster than a polynomial behavior. However, quantum simulators are being developed to efficiently solve quantum problems that are intractable via conventional computing. Some of the most successful quantum simulators are based on ion traps. Their success depends on the ability to achieve long coherence time, precise spin control, and high fidelity in state preparation. In this work, I present calculations that characterizes the oblate Paul trap that creates two-dimensional Coulomb crystals in a triangular lattice and phonon modes. We also calculate the spin-spin Ising-like interaction that can be generated in the oblate Paul trap using the same techinques as the linear radiofrequency Paul trap. In addition, I discuss two possible challenges that arise in the Penning trap: the effects of defects ( namely when Be+ → BeH+) and the creation of a more uniform spin-spin Ising-like interaction. We show that most properties are not significantly influenced by the appearance of defects, and that by adding two potentials to the Penning trap a more uniform spin-spin Ising-like interaction can be achieved. Next, I discuss techniques tfor preparing the ground state of the Ising-like Hamiltonian. In particular, we explore the use of the bang-bang protocol to prepare the ground state and compare optimized results to conventional adiabatic ramps ( the exponential and locally adiabatic ramp ). The bang-bang optimization in general outperforms the exponential; however the locally adiabatic ramp consistently is somewhat better. However, compared to the locally adiabatic ramp, the bang-bang optimization is simpler to implement, and it has the advantage of providingrovide a simple procedure for estimating the
Continuous photodetection model: quantum jumps engineering and hints for experimental verification
Energy Technology Data Exchange (ETDEWEB)
Dodonov, A V [Departamento de Fisica, CCET, Universidade Federal de Sao Carlos, Via Washington Luiz km 235, 13565-905, Sao Carlos, SP (Brazil); Mizrahi, S S [Departamento de Fisica, CCET, Universidade Federal de Sao Carlos, Via Washington Luiz km 235, 13565-905, Sao Carlos, SP (Brazil); Dodonov, V V [Instituto de Fisica, Universidade de BrasIlia, PO Box 04455, 70910-900, BrasIlia, DF (Brazil)
2007-10-15
We examine some aspects of the continuous photodetection model for photocounting processes in cavities. First, we work out a microscopic model that describes the field-detector interaction and deduce a general expression for the Quantum Jump Superoperator (QJS), that shapes the detector's post-action on the field upon a detection. We show that in particular cases our model recovers the QJSs previously proposed ad hoc in the literature and point out that by adjusting the detector parameters one can engineer QJSs. Then we set up schemes for experimental verification of the model. By taking into account the ubiquitous non-idealities, we show that by measuring the lower photocounts moments and the mean waiting time one can check which QJS better describes the photocounting phenomenon.
Chau, H. F.; Wang, Qinan; Wong, Cardythy
2017-02-01
Recently, Chau [Phys. Rev. A 92, 062324 (2015), 10.1103/PhysRevA.92.062324] introduced an experimentally feasible qudit-based quantum-key-distribution (QKD) scheme. In that scheme, one bit of information is phase encoded in the prepared state in a 2n-dimensional Hilbert space in the form (|i > ±|j >) /√{2 } with n ≥2 . For each qudit prepared and measured in the same two-dimensional Hilbert subspace, one bit of raw secret key is obtained in the absence of transmission error. Here we show that by modifying the basis announcement procedure, the same experimental setup can generate n bits of raw key for each qudit prepared and measured in the same basis in the noiseless situation. The reason is that in addition to the phase information, each qudit also carries information on the Hilbert subspace used. The additional (n -1 ) bits of raw key comes from a clever utilization of this extra piece of information. We prove the unconditional security of this modified protocol and compare its performance with other existing provably secure qubit- and qudit-based protocols on market in the one-way classical communication setting. Interestingly, we find that for the case of n =2 , the secret key rate of this modified protocol using nondegenerate random quantum code to perform one-way entanglement distillation is equal to that of the six-state scheme.
Interpretations of Probability in Quantum Mechanics: A Case of "Experimental Metaphysics"
Hellman, Geoffrey
After reviewing paradigmatic cases of "experimental metaphysics" basing inferences against local realism and determinism on experimental tests of Bells theorem (and successors), we concentrate on clarifying the meaning and status of "objective probability" in quantum mechanics. The terms "objective" and "subjective" are found ambiguous and inadequate, masking crucial differences turning on the question of what the numerical values of probability functions measure vs. the question of the nature of the "events" on which such functions are defined. This leads naturally to a 2×2 matrix of types of interpretations, which are then illustrated with salient examples. (Of independent interest are the splitting of "Copenhagen interpretation" into "objective" and "subjective" varieties in one of the dimensions and the splitting of Bohmian hidden variables from (other) modal interpretations along that same dimension.) It is then explained why Everett interpretations are difficult to categorize in these terms. Finally, we argue that Bohmian mechanics does not seriously threaten the experimental-metaphysical case for ultimate randomness and purely physical probabilities.
Interpretations of Probability in Quantum Mechanics: A Case of ``Experimental Metaphysics''
Hellman, Geoffrey
After reviewing paradigmatic cases of “experimental metaphysics” basing inferences against local realism and determinism on experimental tests of Bells theorem (and successors), we concentrate on clarifying the meaning and status of “objective probability” in quantum mechanics. The terms “objective” and “subjective” are found ambiguous and inadequate, masking crucial differences turning on the question of what the numerical values of probability functions measure vs. the question of the nature of the “events” on which such functions are defined. This leads naturally to a 2×2 matrix of types of interpretations, which are then illustrated with salient examples. (Of independent interest are the splitting of “Copenhagen interpretation” into “objective” and “subjective” varieties in one of the dimensions and the splitting of Bohmian hidden variables from (other) modal interpretations along that same dimension.) It is then explained why Everett interpretations are difficult to categorize in these terms. Finally, we argue that Bohmian mechanics does not seriously threaten the experimental-metaphysical case for ultimate randomness and purely physical probabilities.
Hazelgrove, Jenny
2002-04-01
This article explores the impact of the Nuremberg Code on post-Second World War research ethics in Britain. Against the background of the Nuremberg Medical Trial, the Code received international endorsement, but how much did its ethical percepts influence actual research? This paper shows that, despite British involvement in the formulation of the Code, the experience of war-time and changing career structures were more influential in shaping the approach of investigators to their subjects. Where medical debates ensued, primarily over controversial research practices at the British Postgraduate Medical School, Hammersmith Hospital, they were set in the context of a much older division between 'bedside' and 'scientific' medicine. But whatever differences there may have been between those physicians who advocated research and those who questioned its use and ethical basis, most clung to the paternalist assumption that it was the doctor's place to decide what was best for his patients. Faced with rising public and medical criticism of contemporary research practices, the medical élite of the 1960s and 1970s safeguarded the reputation of the profession and medical control of research by negotiating new voluntary codes. In a similar move, their predecessors had helped to negotiate the Nuremberg Code in anticipation of public criticism of experimentation arising from the Nuremberg Medical Trial.
Bhomian Mechanics vs. Standard Quantum Mechanics: a Difference in Experimental Predictions
Szczepanski, Artur
2010-01-01
Standard Quantum Mechanics (QM) predicts an anti-intuitive fenomenon here referred to as "quantum autoscattering", which is excluded by Bhomian Mechanics. The scheme of a gedanken experiment testing the QM prediction is briefly discussed.
Garzelli, M V; Battistoni, G.; Cerutti, F.; Fasso, A.; Ferrari, A.; Gadioli, E.; Ottolenghi, A.; Pinsky, Lawrence S.; Ranft, J.; Sala, P.R.
2006-01-01
A new code, based on the Quantum Molecular Dynamics theoretical approach, has been developed and interfaced to the FLUKA evaporation/fission/Fermi break-up module. At present, this code is undergoing a series of validation tests. In this paper its predictions are compared to measured charged fragment yields and double differential neutron spectra in thin target heavy-ion reactions, at bombarding energies of about 100 MeV/A. The comparisons with the predictions of a modified version of RQMD 2.4 originally developed in Frankfurt, already available in the FLUKA code, are presented and potential improvements are briefly sketched.
DEFF Research Database (Denmark)
Lund-Hansen, Toke; Stobbe, Søren; Julsgaard, Brian
2008-01-01
We present time-resolved spontaneous emission measurements of single quantum dots embedded in photonic crystal waveguides. Quantum dots that couple to a photonic crystal waveguide are found to decay up to 27 times faster than uncoupled quantum dots. From these measurements -factors of up to 0...
A quantitative analysis of model-driven code generation through software experimentation
Papotti, Paulo Eduardo; do Prado, Antonio Francisco; Lopes de Souza, Wanderley; Cirilo, Carlos Eduardo; Ferreira Pires, Luis; Salinesi, C.; Norrie, M.C.; Pastor, O
Recent research results have shown that Model-Driven Development (MDD) is a beneficial approach to develop software systems. The reduction of development time enabled by code generation mechanisms is often acknowledged as an important benefit to be further explored. This paper reports on an
Experimental Study of Quantum Graphs With and Without Time-Reversal Invariance
Anlage, Steven Mark; Fu, Ziyuan; Koch, Trystan; Antonsen, Thomas; Ott, Edward
An experimental setup consisting of a microwave network is used to simulate quantum graphs. The random coupling model (RCM) is applied to describe the universal statistical properties of the system with and without time-reversal invariance. The networks which are large compared to the wavelength, are constructed from coaxial cables connected by T junctions, and by making nodes with circulators time-reversal invariance for microwave propagation in the networks can be broken. The results of experimental study of microwave networks with and without time-reversal invariance are presented both in frequency domain and time domain. With the measured S-parameter data of two-port networks, the impedance statistics and the nearest-neighbor spacing statistics are examined. Moreover, the experiments of time reversal mirrors for networks demonstrate that the reconstruction quality can be used to quantify the degree of the time-reversal invariance for wave propagation. Numerical models of networks are also presented to verify the time domain experiments. We acknowledge support under contract AFOSR COE Grant FA9550-15-1-0171 and the ONR Grant N000141512134.
Quantum memories with zero-energy Majorana modes and experimental constraints
Ippoliti, Matteo; Rizzi, Matteo; Giovannetti, Vittorio; Mazza, Leonardo
2016-06-01
In this work we address the problem of realizing a reliable quantum memory based on zero-energy Majorana modes in the presence of experimental constraints on the operations aimed at recovering the information. In particular, we characterize the best recovery operation acting only on the zero-energy Majorana modes and the memory fidelity that can be therewith achieved. In order to understand the effect of such restriction, we discuss two examples of noise models acting on the topological system and compare the amount of information that can be recovered by accessing either the whole system, or the zero modes only, with particular attention to the scaling with the size of the system and the energy gap. We explicitly discuss the case of a thermal bosonic environment inducing a parity-preserving Markovian dynamics in which the memory fidelity achievable via a read-out of the zero modes decays exponentially in time, independent from system size. We argue, however, that even in the presence of said experimental limitations, the Hamiltonian gap is still beneficial to the storage of information.
Energy Technology Data Exchange (ETDEWEB)
Chang, H. Oh, PhD; Cliff Davis; Richard Moore
2004-11-01
The very high temperature gas-cooled reactors (VHTGRs) are those concepts that have average coolant temperatures above 900 degrees C or operational fuel temperatures above 1250 degrees C. These concepts provide the potential for increased energy conversion efficiency and for high-temperature process heat application in addition to power generation and nuclear hydrogen generation. While all the High Temperature Gas Cooled Reactor (HTGR) concepts have sufficiently high temperatures to support process heat applications, such as desalination and cogeneration, the VHTGR's higher temperatures are suitable for particular applications such as thermochemical hydrogen production. However, the high temperature operation can be detrimental to safety following a loss-of-coolant accident (LOCA) initiated by pipe breaks caused by seismic or other events. Following the loss of coolant through the break and coolant depressurization, air from the containment will enter the core by molecular diffusion and ultimately by natural convection, leading to oxidation of the in-core graphite structures and fuel. The oxidation will release heat and accelerate the heatup of the reactor core. Thus, without any effective countermeasures, a pipe break may lead to significant fuel damage and fission product release. The Idaho National Engineering and Environmental Laboratory (INEEL) has investigated this event for the past three years for the HTGR. However, the computer codes used, and in fact none of the world's computer codes, have been sufficiently developed and validated to reliably predict this event. New code development, improvement of the existing codes, and experimental validation are imperative to narrow the uncertaninty in the predictions of this type of accident. The objectives of this Korean/United States collaboration are to develop advanced computational methods for VHTGR safety analysis codes and to validate these computer codes.
Experimental demonstration of a compiled version of Shor's algorithm with quantum entanglement.
Lanyon, B P; Weinhold, T J; Langford, N K; Barbieri, M; James, D F V; Gilchrist, A; White, A G
2007-12-21
Shor's powerful quantum algorithm for factoring represents a major challenge in quantum computation. Here, we implement a compiled version in a photonic system. For the first time, we demonstrate the core processes, coherent control, and resultant entangled states required in a full-scale implementation. These are necessary steps on the path towards scalable quantum computing. Our results highlight that the algorithm performance is not the same as that of the underlying quantum circuit and stress the importance of developing techniques for characterizing quantum algorithms.
Hémery, Thérèse; Huenerbein, Robert; Fröhlich, Roland; Grimme, Stefan; Hoppe, Dieter
2010-08-20
Experimental investigations as well as high-level quantum chemical calculations are performed on the two epimeric pairs of complexes 4.2 and 6.2 obtained by lithiation of cinnamyl carbamate (1) and 1-naphthyl derivative 5 in the presence of BOX ligands (S,S)- and (R,R)-2. Indeed, in the case of configurationally labile complexes and a dynamic thermodynamic resolution, which is found to take place, one of both epimers is energetically favored. The quantum chemical computations allow the prediction of the enantiomeric excess that can be expected.
O'Brien, J. M.; Young, T. M.; O'Mahoney, D. C.; Griffin, P. C.
2017-07-01
A review of wind turbine aerodynamics research is presented. The review is limited to Horizontal Axis Wind Turbine (HAWT) investigations. The focus is on recent near wake experiments, wake predictions by commercial CFD codes and current FSI and structural modelling attempts. For the near wake, the review considers experiments carried out in controlled conditions whereby the incoming freestream is perpendicular to the rotor plane. Additional anomalies such as wind shear, gusts and yaw transition are not considered. The survey of 3D commercial codes is also focused on HAWT models in parallel flow conditions. Finally, the structural models reviewed are divided into two separate categories: 1) blade deflection and performance under aerodynamic loads, and 2) the vibrational response of blades under aerodynamic loading. The aim is to highlight common trends within near wake experiments and investigate both CFD and FE modelling strategies - to identify current limitations and future opportunities within the sector.
Cruz-Rabadán, Josué S; Miranda-Ríos, Juan; Espín-Ocampo, Guadalupe; Méndez-Tovar, Luis J; Maya-Pineda, Héctor Rubén; Hernández-Hernández, Francisca
2017-01-01
Nocardia spp. are common soil-inhabiting bacteria that frequently infect humans through traumatic injuries or inhalation routes and cause infections, such as actinomycetoma and nocardiosis, respectively. Nocardia brasiliensis is the main aetiological agent of actinomycetoma in various countries. Many bacterial non-coding RNAs are regulators of genes associated with virulence factors. The aim of this work was to identify non-coding RNAs (ncRNAs) expressed during infection conditions and in free-living form ( in vitro ) in Nocardia brasiliensis . The N. brasiliensis transcriptome (predominately brasiliensis infection compared with the in vitro conditions. The results of this work suggest a possible role for these transcripts in the regulation of virulence genes in actinomycetoma pathogenesis.
Cruz-Rabadán, Josué S.; Miranda-Ríos, Juan; Espín-Ocampo, Guadalupe; Méndez-Tovar, Luis J.; Maya-Pineda, Héctor Rubén; Hernández-Hernández, Francisca
2017-01-01
Introduction: Nocardia spp. are common soil-inhabiting bacteria that frequently infect humans through traumatic injuries or inhalation routes and cause infections, such as actinomycetoma and nocardiosis, respectively. Nocardia brasiliensis is the main aetiological agent of actinomycetoma in various countries. Many bacterial non-coding RNAs are regulators of genes associated with virulence factors. Objective: The aim of this work was to identify non-coding RNAs (ncRNAs) expressed during infection conditions and in free-living form (in vitro) in Nocardia brasiliensis. Methods and Result: The N. brasiliensis transcriptome (predominately brasiliensis infection compared with the in vitro conditions. Conclusion: The results of this work suggest a possible role for these transcripts in the regulation of virulence genes in actinomycetoma pathogenesis. PMID:28839491
Experimental benchmark of the NINJA code for application to the Linac4 H‑ ion source plasma
Briefi, S.; Mattei, S.; Rauner, D.; Lettry, J.; Tran, M. Q.; Fantz, U.
2017-10-01
For a dedicated performance optimization of negative hydrogen ion sources applied at particle accelerators, a detailed assessment of the plasma processes is required. Due to the compact design of these sources, diagnostic access is typically limited to optical emission spectroscopy yielding only line-of-sight integrated results. In order to allow for a spatially resolved investigation, the electromagnetic particle-in-cell Monte Carlo collision code NINJA has been developed for the Linac4 ion source at CERN. This code considers the RF field generated by the ICP coil as well as the external static magnetic fields and calculates self-consistently the resulting discharge properties. NINJA is benchmarked at the diagnostically well accessible lab experiment CHARLIE (Concept studies for Helicon Assisted RF Low pressure Ion sourcEs) at varying RF power and gas pressure. A good general agreement is observed between experiment and simulation although the simulated electron density trends for varying pressure and power as well as the absolute electron temperature values deviate slightly from the measured ones. This can be explained by the assumption of strong inductive coupling in NINJA, whereas the CHARLIE discharges show the characteristics of loosely coupled plasmas. For the Linac4 plasma, this assumption is valid. Accordingly, both the absolute values of the accessible plasma parameters and their trends for varying RF power agree well in measurement and simulation. At varying RF power, the H‑ current extracted from the Linac4 source peaks at 40 kW. For volume operation, this is perfectly reflected by assessing the processes in front of the extraction aperture based on the simulation results where the highest H‑ density is obtained for the same power level. In surface operation, the production of negative hydrogen ions at the converter surface can only be considered by specialized beam formation codes, which require plasma parameters as input. It has been demonstrated
Directory of Open Access Journals (Sweden)
Somayeh Gholami
2010-06-01
Full Text Available Introduction: Gamma Knife is an instrument specially designed for treating brain disorders. In Gamma Knife, there are 201 narrow beams of cobalt-60 sources that intersect at an isocenter point to treat brain tumors. The tumor is placed at the isocenter and is treated by the emitted gamma rays. Therefore, there is a high dose at this point and a low dose is delivered to the normal tissue surrounding the tumor. Material and Method: In the current work, the MCNP simulation code was used to simulate the Gamma Knife. The calculated values were compared to the experimental ones and previous works. Dose distribution was compared for different collimators in a water phantom and the Zubal brain-equivalent phantom. The dose profiles were obtained along the x, y and z axes. Result: The evaluation of the developed code was performed using experimental data and we found a good agreement between our simulation and experimental data. Discussion: Our results showed that the skull bone has a high contribution to both scatter and absorbed dose. In other words, inserting the exact material of brain and other organs of the head in digital phantom improves the quality of treatment planning. This work is regarding the measurement of absorbed dose and improving the treatment planning procedure in Gamma-Knife radiosurgery in the brain.
Experimental demonstration of efficient quantum state tomography of matrix product states.
Zhao, Yuan-Yuan; Hou, Zhibo; Xiang, Guo-Yong; Han, Yong-Jian; Li, Chuan-Feng; Guo, Guang-Can
2017-04-17
Quantum state tomography is a key technology for fully determining a quantum state. Unfortunately, standard quantum state tomography is intractable for general many-body quantum states, because the number of measurements and the post-processing time increase exponentially with the size of the system. However, for the matrix product states (MPSs), there exists an efficient method using linearly scaled local measurements and polynomially scaled post-processing times. In this study, we demonstrate the validity of the method in practice by reconstructing a four-photon MPS from its local two- or three-photon reduced-density matrices with the presence of statistical errors and systematical errors in experiment.
2016-01-26
wavelength upon fabrication. This wavelength is ideal for strained InGaAs quantum well structures which can be embedded into the GaAs/AlGaAs matrix[3... quantum dot or an InGaAs quantum well . The band gap can be varied in addition to include either one or two electronic levels of a multi-level system...Electronic and Optoelectronic Devices,” SAND99-0921, July 1999. 4. R. L. S. Devine, “Photoluminescence characterization of InGaAs /GaAs quantum well
Mishra, Rashmi; Joshi, Bhawani Datt; Srivastava, Anubha; Tandon, Poonam; Jain, Sudha
2014-01-01
The study concentrates on an important natural product, phthalide isoquinoline alkaloid Corlumine (COR) [(6R)-6-[(1S)-1,2,3,4-Tetrahydro-6,7-dimethoxy-2-methylisoquinolin-1-yl] furo [3,4-e]-1,3-benzodioxol-8(6H)-one] well known to exhibit spasmolytic and GABA antagonist activity. It was fully characterized by a variety of experimental methods including vibrational spectroscopy (IR and Raman), thermal analysis (DSC), UV and SEM. For a better interpretation and analysis of the results quantum chemical calculations employing DFT were also performed. TD-DFT was employed to elucidate electronic properties for both gaseous and solvent environment using IEF-PCM model. Graphical representation of HOMO and LUMO would provide a valuable insight into the nature of reactivity and some of the structural and physical properties of the title molecule. The structure-activity relationship have been interpreted by mapping electrostatic potential surface (MEP), which is valuable information for the quality control of medicines and drug-receptor interactions. Stability of the molecule arising from hyper conjugative interactions, charge delocalisation has been analyzed using natural bond orbital (NBO) analysis. Computation of thermodynamical properties would help to have a deep insight into the molecule for further applications.
Experimental benchmark and code validation for airfoils equipped with passive vortex generators
Baldacchino, D.; Manolesos, M.; Simao Ferreira, C.; Gonz?alez Salcedo, A; Aparicio, M.; Chaviaropoulos, T.; Diakakis, K.; Florentie, L.; Garci??a, M.; Papadakis, G; So?rensen, N.N.; Timmer, W.A.; Troldborg, N.; Voutsinas, S.; van Zuijlen, A.H.
2016-01-01
Experimental results and complimentary computations for airfoils with vortex generators are compared in this paper, as part of an e_ort within the AVATAR project to develop tools for wind turbine blade control devices. Measurements from two airfoils equipped with passive vortex generators, a 30%
Energy Technology Data Exchange (ETDEWEB)
Chung, Myung Kyoon; Oh, Woo Hyoung; Song, Jae Wook [Korea Advanced Institute of Science and Technology, Taejon (Korea)
1999-03-01
The present study is aimed at developing a computational code for design and performance prediction of an axial-flow pump. The proposed performance prediction method is tested against a model axial-flow pump streamline curvature method. The preliminary design is made by using the ideal velocity triangles at inlet and exit and the three dimensional blade shape is calculated by employing the free vortex design method. Then the detailed blading design is carried out by using experimental database of double circular arc cambered hydrofoils. To computationally determine the design incidence, deviation, blade camber, solidity and stagger angle, a number of correlation equations are developed form the experimental database and a theorical formula for the lift coefficient is adopted. A total of 8 equations are solved iteratively using an under-relaxation factor. An experimental measurement is conducted under a non-cavitating condition to obtain the off-design performance curve and also a cavitation test is carried out by reducing the suction pressure. The experimental results are very satisfactorily compared with the predictions by the streamline curvature method. 28 refs., 26 figs., 11 tabs. (Author)
Experimental results of an optical 20 MBPS bipolar coded raised cosine digital communications link
Durrant, Randy; Kennedy, William P.
1990-07-01
The use of raised cosine shaped symbols has been proposed for optical digital communications. The raised cosine pulse shape reduces the receiver signal bandwidth to that of the data rate while simultaneously minimizing inter-symbol interference. This has the effect of increasing receiver sensitivity due to the noise density characteristics of transimpedance amplifiers when bandwidth is reduced. Receiver sensitivity is an essential criteria for free space laser communication. An optical communications experiment was conducted consisting of a laser transmitter modulated by a 20 megabit per second bipolar coded raised cosine bit stream and a matched filter receiver utilizing an APD detector and a transimpedance amplifier. Pulse shaping and matched filter circuits were implemented using a tapped delay line filter type topology. The bit error rate of the receiver as a function of incident optical power was measured and is compared to predicted performance. Implementation losses are accounted for in terms of matched filter mismatch loss, inter-symbol interference, sample time uncertainties, and system nonlinearities.
Experimental Definition and Validation of Protein Coding Transcripts in Chlamydomonas reinhardtii
Energy Technology Data Exchange (ETDEWEB)
Kourosh Salehi-Ashtiani; Jason A. Papin
2012-01-13
Algal fuel sources promise unsurpassed yields in a carbon neutral manner that minimizes resource competition between agriculture and fuel crops. Many challenges must be addressed before algal biofuels can be accepted as a component of the fossil fuel replacement strategy. One significant challenge is that the cost of algal fuel production must become competitive with existing fuel alternatives. Algal biofuel production presents the opportunity to fine-tune microbial metabolic machinery for an optimal blend of biomass constituents and desired fuel molecules. Genome-scale model-driven algal metabolic design promises to facilitate both goals by directing the utilization of metabolites in the complex, interconnected metabolic networks to optimize production of the compounds of interest. Using Chlamydomonas reinhardtii as a model, we developed a systems-level methodology bridging metabolic network reconstruction with annotation and experimental verification of enzyme encoding open reading frames. We reconstructed a genome-scale metabolic network for this alga and devised a novel light-modeling approach that enables quantitative growth prediction for a given light source, resolving wavelength and photon flux. We experimentally verified transcripts accounted for in the network and physiologically validated model function through simulation and generation of new experimental growth data, providing high confidence in network contents and predictive applications. The network offers insight into algal metabolism and potential for genetic engineering and efficient light source design, a pioneering resource for studying light-driven metabolism and quantitative systems biology. Our approach to generate a predictive metabolic model integrated with cloned open reading frames, provides a cost-effective platform to generate metabolic engineering resources. While the generated resources are specific to algal systems, the approach that we have developed is not specific to algae and
Karthick, T.; Tandon, Poonam; Singh, Swapnil; Agarwal, Parag; Srivastava, Anubha
2017-02-01
The investigations of structural conformers, molecular interactions and vibrational characterization of pharmaceutical drug are helpful to understand their behaviour. In the present work, the 2D potential energy surface (PES) scan has been performed on the dihedral angles C6sbnd O4sbnd S1sbnd C5 and C25sbnd S22sbnd O19sbnd C16 to find the stable conformers of busulfan. In order to show the effects of long range interactions, the structures on the global minima of PES scan have been further optimized by B3LYP/6-311 ++G(d,p) method with and without empirical dispersion functional in Gaussian 09W package. The presence of n → σ* and σ → σ* interactions which lead to stability of the molecule have been predicted by natural bond orbital analysis. The strong and weak hydrogen bonds between the functional groups of busulfan were analyzed using quantum topological atoms in molecules analysis. In order to study the long-range forces, such as van der Waals interactions, steric effect in busulfan, the reduced density gradient as well as isosurface defining these interactions has been plotted using Multiwfn software. The spectroscopic characterization on the solid phase of busulfan has been studied by experimental FT-IR and FT-Raman spectra. From the 13C and 1H NMR spectra, the chemical shifts of individual C and H atoms of busulfan have been predicted. The maximum absorption wavelengths corresponding to the electronic transitions between the highest occupied molecular orbital and the lowest unoccupied molecular orbital of busulfan have been found by UV-vis spectrum.
Karthick, T; Tandon, Poonam; Singh, Swapnil; Agarwal, Parag; Srivastava, Anubha
2017-02-15
The investigations of structural conformers, molecular interactions and vibrational characterization of pharmaceutical drug are helpful to understand their behaviour. In the present work, the 2D potential energy surface (PES) scan has been performed on the dihedral angles C6O4S1C5 and C25S22O19C16 to find the stable conformers of busulfan. In order to show the effects of long range interactions, the structures on the global minima of PES scan have been further optimized by B3LYP/6-311++G(d,p) method with and without empirical dispersion functional in Gaussian 09W package. The presence of n→σ* and σ→σ* interactions which lead to stability of the molecule have been predicted by natural bond orbital analysis. The strong and weak hydrogen bonds between the functional groups of busulfan were analyzed using quantum topological atoms in molecules analysis. In order to study the long-range forces, such as van der Waals interactions, steric effect in busulfan, the reduced density gradient as well as isosurface defining these interactions has been plotted using Multiwfn software. The spectroscopic characterization on the solid phase of busulfan has been studied by experimental FT-IR and FT-Raman spectra. From the (13)C and (1)H NMR spectra, the chemical shifts of individual C and H atoms of busulfan have been predicted. The maximum absorption wavelengths corresponding to the electronic transitions between the highest occupied molecular orbital and the lowest unoccupied molecular orbital of busulfan have been found by UV-vis spectrum. Copyright © 2016 Elsevier B.V. All rights reserved.
DEFF Research Database (Denmark)
Andersen, Kasper Langebjerg; Nielsen, Henrik
2012-01-01
The ciliate Tetrahymena thermophila is an important eukaryotic model organism that has been used in pioneering studies of general phenomena, such as ribozymes, telomeres, chromatin structure and genome reorganization. Recent work has shown that Tetrahymena has many classes of small RNA molecules...... class was small nucleolar RNAs (snoRNAs), many of which are formed by an unusual maturation pathway. The modifications guided by the snoRNAs were analyzed bioinformatically and experimentally and many Tetrahymena-specific modifications were found, including several in an essential, but not conserved...
Quantum Phase Transitions in Quantum Dots
Rau, I. G.; Amasha, S.; Oreg, Y.; Goldhaber-Gordon, D.
2013-01-01
This review article describes theoretical and experimental advances in using quantum dots as a system for studying impurity quantum phase transitions and the non-Fermi liquid behavior at the quantum critical point.
Organic molecule fluorescence as an experimental test-bed for quantum jumps in thermodynamics.
Browne, Cormac; Farrow, Tristan; Dahlsten, Oscar C O; Taylor, Robert A; Vlatko, Vedral
2017-08-01
We demonstrate with an experiment how molecules are a natural test bed for probing fundamental quantum thermodynamics. Single-molecule spectroscopy has undergone transformative change in the past decade with the advent of techniques permitting individual molecules to be distinguished and probed. We demonstrate that the quantum Jarzynski equality for heat is satisfied in this set-up by considering the time-resolved emission spectrum of organic molecules as arising from quantum jumps between states. This relates the heat dissipated into the environment to the free energy difference between the initial and final state. We demonstrate also how utilizing the quantum Jarzynski equality allows for the detection of energy shifts within a molecule, beyond the relative shift.
Experimental measurement-device-independent quantum digital signatures over a metropolitan network
Yin, Hua-Lei; Wang, Wei-Long; Tang, Yan-Lin; Zhao, Qi; Liu, Hui; Sun, Xiang-Xiang; Zhang, Wei-Jun; Li, Hao; Puthoor, Ittoop Vergheese; You, Li-Xing; Andersson, Erika; Wang, Zhen; Liu, Yang; Jiang, Xiao; Ma, Xiongfeng; Zhang, Qiang; Curty, Marcos; Chen, Teng-Yun; Pan, Jian-Wei
2017-04-01
Quantum digital signatures (QDSs) provide a means for signing electronic communications with information-theoretic security. However, all previous demonstrations of quantum digital signatures assume trusted measurement devices. This renders them vulnerable against detector side-channel attacks, just like quantum key distribution. Here we exploit a measurement-device-independent (MDI) quantum network, over a metropolitan area, to perform a field test of a three-party MDI QDS scheme that is secure against any detector side-channel attack. In so doing, we are able to successfully sign a binary message with a security level of about 10-7. Remarkably, our work demonstrates the feasibility of MDI QDSs for practical applications.
Du, Jinjian; Cao, Leiming; Zhang, Kai; Jing, Jietai
2017-06-01
Extensive attention has been drawn in generating multimode quantum states in recent years. Many efforts have been made during the last decade to produce such states. In this paper, we have experimentally demonstrated a scheme for generating a multi-spatial-mode quantum light source by a non-degenerated four-wave mixing process with a conical pump and a conical probe in a hot atomic vapor cell. The degree of the intensity-difference squeezing between the generated twin beams is about -4.1 dB. Due to the similar conical shape of the concentric quantum correlated beams, both the amplified probe and the generated conjugate beams can be decomposed into many angular modes. We have also experimentally verified the multi-spatial-mode nature of the generated quantum correlation by comparing the noise levels' variation tendencies of global attenuation and local cutting attenuations. In addition, we have also found the optimal values of each parameter in this scheme for further applications. Due to our scheme's advantages such as compactness, phase-insensitivity, and easy scalability, we have already shown a promising candidate for generating multi-spatial-mode quantum states, which may find potential applications in quantum metrology and quantum imaging, such as quantum-enhanced superresolution and the generation of multiple quantum correlated images.
Zhao, X L; Han, J X
2013-12-01
Traditional Chinese Medicine (TCM) developed based on ancient Chinese philosophy. Its characteristics include abstract theories, fuzzy concepts, subjective diagnostic methods and it lacks clarity, and rigor as well as vindication from modern sciences, which makes development of TCM remain stagnant. Thus, how to free the theory of TCM from heavy philosophy to achieve separation of medicine and philosophy, and to use the contemporary cutting-edge science and technology to transform the theory of TCM and then to achieve its scientific paradigm shift, is a way for TCM to get out of the woods. This article, focusing on the problems existing in the development of the modernization of TCM, introduces the concept, the connotation as well as the important role of Quantum TCM in the modernization of TCM. Additionally, based on the view that the body's electromagnetic radiation can characterize the human "Qi" in TCM, we discuss several experimental technology systems for the diagnosis of Quantum TCM in detail. By analyzing and comparing these technology systems, we come to the conclusion that the biophoton analytical technology (BPAT) is more worthy of further study in building the experimental technology system for the diagnosis of Quantum TCM.
X-ray synchrotron microdosimetry: Experimental benchmark of a general-purpose Monte Carlo code
Energy Technology Data Exchange (ETDEWEB)
Hugtenburg, R.P. [Medical Physics and Clinical Engineering, School of Medicine, Swansea University, Singleton Park, Swansea SA2 8PP (United Kingdom); Queen Elizabeth Medical Centre, University Hospital Birmingham, NHS Trust, Birmingham (United Kingdom)], E-mail: r.p.hugtenburg@swansea.ac.uk; Baker, A.E.R. [School of Physics and Astronomy, University of Birmingham, Birmingham (United Kingdom); Green, S. [Queen Elizabeth Medical Centre, University Hospital Birmingham, NHS Trust, Birmingham (United Kingdom)
2009-03-15
Microdosimetry is useful in mixed-field radiation treatment strategies but relies on an understanding of electron physics at sub-micron dimensions. Monochromatic synchrotron light will be valuable in the development of Monte Carlo models of radiation transport at this length scale. In addition, synchrotron light offers new treatment strategies benefiting from high degrees of brightness and coherence including binary therapies such as photoactivation therapy (PAT) utilising photoelectric enhancement occurring in the kilovoltage range. Microdosimetric spectra for monoenergetic beams have been obtained in the range 15-33 keV with a tissue-equivalent proportional counter (TEPC) and have been compared to Monte Carlo calculations based on atomic models initially. Transport of electrons in molecular systems can also be considered where fundamental interaction data are also obtainable in synchrotron beams via photon scattering experiments utilising the optical model. In the absence of data from liquid water systems, MOSFET and silica-based optical fibre TLD are emerging contenders for experimental verification of microdosimetric spectra in the solid-state and glassy-state phases, respectively.
Fitting a simple model of inelastic scattering in Monte Carlo code to experimental data
Stary, V
1999-01-01
Monte Carlo simulations are a very useful tool for simulating many physical processes. The method has often been used for electron microscopy, spectroscopy and microanalysis. In this paper, the backscattering coefficient and coefficient of elastic reflection in the energy range 0.2-5 keV for C, Al, Cu, Ag and Au is simulated and compared with literature data. For the elastic cross sections the program PWADIR was used, whereas for inelastic ones the simple hyperbolic distribution of energy losses was utilized. Due to the hyperbolic shape, one free parameter, the minimal energy loss W sub m sub i sub n appears. This quantity hardly influences the dependence of the backscattering coefficient on primary energy, but strongly influences the energy dependence of the coefficient of elastic reflection. By comparison of the calculated and measured values of this coefficient we were able to find the optimal values of W sub m sub i sub n , and, due to mutual dependence, the 'experimental' values of the inelastic mean fre...
Zhang, Jingfu; Cucchietti, Fernando M.; Laflamme, Raymond; Suter, Dieter
2017-04-01
Systems passing through quantum critical points at finite rates have a finite probability of undergoing transitions between different eigenstates of the instantaneous Hamiltonian. This mechanism was proposed by Kibble as the underlying mechanism for the formation of topological defects in the early universe and by Zurek for condensed matter systems. Here, we use a system of nuclear spins as an experimental quantum simulator undergoing a non-equilibrium quantum phase transition. The experimental data confirm the validity of the Kibble-Zurek mechanism of defect formation.
Directory of Open Access Journals (Sweden)
Anireddy S.N. Reddy
2012-02-01
Full Text Available Extensive alternative splicing (AS of precursor mRNAs (pre-mRNAs in multicellular eukaryotes increases the protein-coding capacity of a genome and allows novel ways to regulate gene expression. In fowering plants, up to 48% of intron-containing genes exhibit AS. However, the full extent of AS in plants is not yet known, as only a few high throughput RNA-Seq studies have been performed. As the cost of obtaining RNA-Seq reads continues to fall, it is anticipated that huge amounts of plant sequence data will accumulate and help in obtaining a more complete picture of AS in plants. Although it is not an onerous task to obtain hundreds of millions of reads using high throughput sequencing technologies, computational tools to accurately predict and visualize AS are still being developed and refined. This review will discuss the tools to predict and visualize transcriptome-wide AS in plants using short reads and highlight their limitations. Comparative studies of AS events between plants and animals have revealed that there are major differences in the most prevalent types of AS events, suggesting that plants and animals differ in the way they recognize exons and introns. Extensive studies have been performed in animals to identify cis-elements involved in regulating AS, especially in exon skipping. However, such studies are in their infancy in plants. Here, we review the current state of research on splicing regulatory elements (SREs and briefly discuss emerging experimental and computational tools to identify cis-elements involved in regulation of AS in plants. The availability of curated alternative splice forms in plants makes it possible to use computational tools to predict SREs involved in AS regulation, which can then be verified experimentally. Such studies will permit identification of plant-specific features involved in AS regulation and contribute to deciphering the splicing code in plants.
Palmer, Denni T; Kirby, Robert
2005-01-01
We have developed an experimental research program to the study of the photoemission properties of copper photocathodes as a function of various plasma cleaning/etching parameters. The quantum efficiency, QE, and topology, Ra and Rpp, of Copper Photocathodes, , will be monitored while undergoing plasma cleaning/etching process. We will monitor the QE as a function of time for the various test coupons while we optimize the various plasma processing parameters. In addition, surface topology, will be studied to determine the suitability of the cleaning/etching process to produce an acceptable photoemitter. We propose to use two metrics in the evaluation of the plasma cleaning process as an acceptable cleaning method for metallic photocathodes, Quantum Efficiency versus Wavelength and Surface roughness: Ra and Rpp represent the Average Roughness and Peak to Peak Roughness parameters, respectively.
Experimental Study of Low Density Quantum Hall Fabry-Perot Interferometer
Glinskis, Simas; An, Sanghun; Kang, Woowon; Ocola, Leonidas; Pfeiffer, Loren; West, Ken; Baldwin, Kirk
2015-03-01
In this talk we report on study of interference oscillations observed in Fabry-Perot 1 . 5 μm diameter interferometers fabricated from low density, high mobility AlGaAs/GaAs heterostructures. The Fabry-Perot interferometers were fabricated using e-beam lithography and inductively coupled plasma etching to minimize sample damage. Optimization of the quantum point contacts were made by systematically varying the etching depth and monitoring the resistance of the device. So far we have been able to detect clear interference oscillations which are observed at integer quantum Hall states. The interference oscillations occur in the low magnetic field side of the Hall plateaus when there is substantial backscattering at the quantum point contacts. A linear relationship between filled Landau levels and oscillation frequencies establishes that our interferometers are in the Coulomb dominated regime described by the interacting model of quantum Hall Fabry-Perot interferometers. Study of interference oscillations in the fractional quantum Hall states are currently under progress and will be discussed.
Energy Technology Data Exchange (ETDEWEB)
Xavier, G B; Vilela de Faria, G; Temporao, G P; Von der Weid, J P [Centre for Telecommunication Studies, Pontifical Catholic University of Rio de Janeiro-R Marques de Sao Vicente 225 Gavea, Rio de Janeiro (Brazil); Walenta, N; Gisin, N; Zbinden, H [GAP-Optique, University of Geneva, rue de l' Ecole-de-Medecine 20, CH-1211 Geneva 4 (Switzerland)], E-mail: guix@opto.cetuc.puc-rio.br
2009-04-15
In this paper we demonstrate an active polarization drift compensation scheme for optical fibres employed in a quantum key distribution experiment with polarization encoded qubits. The quantum signals are wavelength multiplexed in one fibre along with two classical optical side channels that provide the control information for the polarization compensation scheme. This set-up allows us to continuously track any polarization change without the need to interrupt the key exchange. The results obtained show that fast polarization rotations of the order of 40{pi} rad s{sup -1} are effectively compensated for. We demonstrate that our set-up allows continuous quantum key distribution even in a fibre stressed by random polarization fluctuations. Our results pave the way for Bell-state measurements using only linear optics with parties separated by long-distance optical fibres.
Controlled Alternate Quantum Walks based Quantum Hash Function.
Li, Dan; Yang, Yu-Guang; Bi, Jing-Lin; Yuan, Jia-Bin; Xu, Juan
2018-01-09
Through introducing controlled alternate quantum walks, we present controlled alternate quantum walks (CAQW) based quantum hash function. CAQW based quantum hash function have excellent security, outstanding statistical performance and splendid expansibility. Furthermore, due to the structure of alternate quantum walks, implementing CAQW based quantum hash function significantly reduces the resources necessary for its feasible experimental realization than implementing other quantum hash functions.
Leonard, Edward, Jr.; Beck, Matthew; Thorbeck, Ted; Zhu, Shaojiang; Howington, Caleb; Nelson, Jj; Plourde, Britton; McDermott, Robert
We describe the characterization of a single flux quantum (SFQ) pulse generator cofabricated with a superconducting quantum circuit on a single chip. Resonant trains of SFQ pulses are used to induce coherent qubit rotations on the Bloch sphere. We describe the SFQ drive characteristics of the qubit at the fundamental transition frequency and at subharmonics (ω01 / n , n = 2 , 3 , 4 , ⋯). We address the issue of quasiparticle poisoning due to the proximal SFQ pulse generator, and we characterize the fidelity of SFQ-based rotations using randomized benchmarking. Present address: IBM T.J. Watson Research Center.
The complementarity relations of quantum coherence in quantum information processing.
Pan, Fei; Qiu, Liang; Liu, Zhi
2017-03-08
We establish two complementarity relations for the relative entropy of coherence in quantum information processing, i.e., quantum dense coding and teleportation. We first give an uncertainty-like expression relating local quantum coherence to the capacity of optimal dense coding for bipartite system. The relation can also be applied to the case of dense coding by using unital memoryless noisy quantum channels. Further, the relation between local quantum coherence and teleportation fidelity for two-qubit system is given.
DEFF Research Database (Denmark)
Wang, Qin; Stobbe, Søren; Nielsen, Henri Thyrrestrup
We have systematically measured the variation of the spontaneous emission rate with polarization for self-assembled single quantum dots in two-dimensional photonic crystal membranes and obtained a maximum anisotropy factor of 6 between the decay rates of the two nondegenerate bright exciton states....
Foulkes, Stephen
2013-04-01
Monte Carlo simulations of the Freedman-Clauser experiment are used to test the Copenhagen interpretation and a local realistic interpretation of Quantum Mechanics. The simulated results are compared to the actual results of the experiment which confirmed the quantum mechanical calculation for nine different relative angles between the two polarization analyzers. For each simulation 5x10^7 total simulated photon pairs were generated at each relative angle. The Copenhagen interpretation model closely followed the general shape of the theoretical calculation but differed from the calculated values by 2.5% to 3.3% for angles less than or equal to π/8 and differed by 15.0% to 52.5% for angles greater than or equal to 3π/8. The local realistic interpretation model did not replicate the experimental results but was generally within 1% of a classical calculation for all analyzer angles. An alternative, ``fuzzy polarization'' interpretation wherein the photon polarization is not assumed to have a fixed value, yielded values within 1% of the quantum mechanical calculation.
Garcia-Escartin, Juan Carlos; Chamorro-Posada, Pedro
2011-01-01
Quantum algorithms and protocols are often presented as quantum circuits for a better understanding. We give a list of equivalence rules which can help in the analysis and design of quantum circuits. As example applications we study quantum teleportation and dense coding protocols in terms of a simple XOR swapping circuit and give an intuitive picture of a basic gate teleportation circuit.
Directory of Open Access Journals (Sweden)
Reza Bagheri
2017-02-01
Full Text Available In this work, linear and mass attenuation coefficients, effective atomic number and electron density, mean free paths, and half value layer and 10th value layer values of barium–bismuth–borosilicate glasses were obtained for 662 keV, 1,173 keV, and 1,332 keV gamma ray energies using MCNP-4C code and XCOM program. Then obtained data were compared with available experimental data. The MCNP-4C code and XCOM program results were in good agreement with the experimental data. Barium–bismuth–borosilicate glasses have good gamma ray shielding properties from the shielding point of view.
Introduction to quantum information science
Hayashi, Masahito; Kawachi, Akinori; Kimura, Gen; Ogawa, Tomohiro
2015-01-01
This book presents the basics of quantum information, e.g., foundation of quantum theory, quantum algorithms, quantum entanglement, quantum entropies, quantum coding, quantum error correction and quantum cryptography. The required knowledge is only elementary calculus and linear algebra. This way the book can be understood by undergraduate students. In order to study quantum information, one usually has to study the foundation of quantum theory. This book describes it from more an operational viewpoint which is suitable for quantum information while traditional textbooks of quantum theory lack this viewpoint. The current book bases on Shor's algorithm, Grover's algorithm, Deutsch-Jozsa's algorithm as basic algorithms. To treat several topics in quantum information, this book covers several kinds of information quantities in quantum systems including von Neumann entropy. The limits of several kinds of quantum information processing are given. As important quantum protocols,this book contains quantum teleport...
Energy Technology Data Exchange (ETDEWEB)
Romero, L.; Travesi, A.
1983-07-01
The REPOL code, performs the fitting a set of experimental data, with a polynomial of mth. degree (max. 10), using the Least Squares Criterion. further, it presents the graphic plotting of the fitted polynomial, in the appropriate coordinates axes system, by a plotter. An additional option allows also the graphic plotting of the experimental data, used for the fit. The necessary data to execute this code, are asked to the operator in the screen, in a iterative way, by screen-operator dialogue, and the values are introduced through the keyboard. This code is written in Fortran IV, and because of its structure programming in subroutine blocks, can be adapted to any computer with graphic screen and keyboard terminal, with a plotter serial connected to it, whose Software has the Hewlett Packard Graphics 1000. (Author) 5 refs.
Directory of Open Access Journals (Sweden)
I. Lorite
2015-03-01
Full Text Available The agglomeration state facilitates particle-particle interaction which produces important effects in the phonon confinement effects at the nanoscale. A partial phonon transmission between close nanoparticles yields a lower momentum conservation relaxation than in a single isolated nanoparticle. It means a larger red shift and broadening of the Raman modes than the expected ones for Raman quantum confinement effects. This particle-particle interaction can drive to error when Raman responses are used to estimate the size of the nanoscaled materials. In this work different corrections are suggested to overtake this source of error.
Energy Technology Data Exchange (ETDEWEB)
Lorite, I., E-mail: lorite@physik.uni-leipzig.de [Electroceramic Department, Instituto de Cerámica y Vidrio, CSIC, Kelsen 5, 28049, Madrid (Spain); Division of Superconductivity and Magnetism, Faculty of Physics and Earth Sciences, Linnestrasse 5, D-04103 Leipzig (Germany); Romero, J. J.; Fernandez, J. F. [Electroceramic Department, Instituto de Cerámica y Vidrio, CSIC, Kelsen 5, 28049, Madrid (Spain)
2015-03-15
The agglomeration state facilitates particle-particle interaction which produces important effects in the phonon confinement effects at the nanoscale. A partial phonon transmission between close nanoparticles yields a lower momentum conservation relaxation than in a single isolated nanoparticle. It means a larger red shift and broadening of the Raman modes than the expected ones for Raman quantum confinement effects. This particle-particle interaction can drive to error when Raman responses are used to estimate the size of the nanoscaled materials. In this work different corrections are suggested to overtake this source of error.
Experimental and Quantum-mechanical Investigation of the Vinylsilane-Iminium Ion Cyclization
DEFF Research Database (Denmark)
Kværnø, Lisbet; Norrby, Per-Ola; Tanner, David Ackland
2003-01-01
be obtained for iminium species derived from 7. Quantum-mechanical investigations of the general reaction mechanism underlined the lack of reactivity of ketiminium species and also convincingly explained the observed diastereoselectivities of aldiminium species. The calculations further revealed that (Z......)-vinylsilanes cyclize via a silicon-stabilized b-carbocation, and that any formal aza-Cope rearrangement of the starting material to an allylsilane-iminium species does not take place in a concerted fashion. However, the calculations show that the aza-Cope rearrangement precedes cyclization for the corresponding (E...
Quantum information processing
National Research Council Canada - National Science Library
Leuchs, Gerd; Beth, Thomas
2003-01-01
... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5 SimulationofHamiltonians... References... 1 1 1 3 5 8 10 2 Quantum Information Processing and Error Correction with Jump Codes (G. Alber, M. Mussinger...
Naik, Gururaj V.; Welch, Alex J.; Dionne, Jennifer A.
2016-09-01
Plasmon resonances in metallic nanoparticles result in enhanced light absorption and hot carrier generation. Although hot carriers are short-lived, their energy can be extracted in optical form resulting in photon upconversion. Two low energy photons absorbed by a plasmonic nanostructure, create a hot electron and a hot hole. These hot carriers get injected into an adjacent semiconductor quantum well where they radiatively recombine to emit a higher energy photon resulting in photon upconversion. This process involves injection of an electron and a hole across the same interface making it charge neutral. The upconversion emission has a linear dependence on the incident light intensity, making it promising for applications requiring low power operation. Theoretical studies show that a silver/semiconductor system can have an ideal efficiency of 25%. Our experimental demonstration of this new scheme utilizes GaN/InGaN quantum wells decorated with both silver and gold. The use of two metals reduces band-bending in the semiconductor. Illuminating the sample with light spanning wavelengths of 500-540 nm produces upconversion photoluminescence centered at 435 nm. Control samples including undecorated quantum wells and metal nanostructures on a glass substrate do not show any upconversion ruling out possibilities of upconversion in individual materials. Further, the linear dependence of the upconverted light intensity with incident intensity rules out any non-linear or Auger mediated mechanisms. We will describe how this hot carrier upconversion process promises to be broadband, tunable, and more efficient than existing solid-state upconversion schemes, and discuss potential applications in solar energy, security, and photodetection applications.
Platonov, A.; Zaitsev, Ie.; Opalski, L. J.
2017-08-01
The paper presents an overview of design methodology and results of experiments with a Prototype of highly efficient optimal adaptive feedback communication systems (AFCS), transmitting low frequency analog signals without coding. The paper emphasizes the role of the forward transmitter saturation as the factor that blocked implementation of theoretical results of pioneer (1960-1970s) and later research on FCS. Deepened analysis of the role of statistical fitting condition in adequate formulation and solution of AFCS optimization task is given. Solution of the task - optimal transmission/reception algorithms is presented in the form useful for elaboration of the hardware/software Prototype. A notable particularity of the Prototype is absence of the encoding/decoding units, whose functions are realized by the adaptive pulse amplitude modulator (PAM) of the forward transmitter (FT) and estimating/controlling algorithm in the receiver of base station (BS). Experiments confirm that the Prototype transmits signals from FT to BS "perfectly": with the bit rate equal to the capacity of the system, and with limit energy [J/bit] and spectral [bps/Hz] efficiency. Another, not less important and confirmed experimentally, particularity of AFCS is its capability to adjust parameters of FT and BS to the characteristics of scenario of application and maintain the ideal regime of transmission including spectralenergy efficiency. AFCS adjustment can be made using BS estimates of mean square error (MSE). The concluding part of the paper contains discussion of the presented results, stressing capability of AFCS to solve problems appearing in development of dense wireless networks.
Directory of Open Access Journals (Sweden)
Nicola Bosso
2014-01-01
Full Text Available The work shows the use of a scaled roller rig to validate a real time wheel-rail contact code developed to study the wheel rail adhesion and the wear evolution. The code allows the profiles to change at each time step in order to take into account the material loss due to the wear process. The contact code replicates a testing machine composed of a roller rig with a prototype of a single suspended wheelset pressed onto it with a variable load. The roller rig, developed at Politecnico di Torino, is used to validate and optimize the contact code referring to experimental data directly measured in real time. The test bench, in fact, allows measurement of specific kinematical quantities and forces that are elaborated by the real-time code in order to produce numerical results for comparison with the experimental ones. This approach can be applied both to the determination of wheel-rail adhesion and to the wear process. The test rig is also equipped with a laser profilometer that allows measurement of the wheel and rail profiles with a very high accuracy.
Directory of Open Access Journals (Sweden)
Sadiq Muhammad
2014-06-01
Full Text Available Quantum methods allow us to reduce communication complexity of some computational tasks, with several separated partners, beyond classical constraints. Nevertheless, experimental demonstrations of this have thus far been limited to some abstract problems, far away from real-life tasks. We show here, and demonstrate experimentally, that the power of reduction of communication complexity can be harnessed to gain an advantage in a famous, immensely popular, card game—bridge. The essence of a winning strategy in bridge is efficient communication between the partners. The rules of the game allow only a specific form of communication, of very low complexity (effectively, one has strong limitations on the number of exchanged bits. Surprisingly, our quantum technique does not violate the existing rules of the game (as there is no increase in information flow. We show that our quantum bridge auction corresponds to a biased nonlocal Clauser-Horne-Shimony-Holt game, which is equivalent to a 2→1 quantum random access code. Thus, our experiment is also a realization of such protocols. However, this correspondence is not complete, which enables the bridge players to have efficient strategies regardless of the quality of their detectors.
Experimental integration of quantum key distribution and gigabit-capable passive optical network
Sun, Wei; Wang, Liu-Jun; Sun, Xiang-Xiang; Mao, Yingqiu; Yin, Hua-Lei; Wang, Bi-Xiao; Chen, Teng-Yun; Pan, Jian-Wei
2018-01-01
Quantum key distribution (QKD) ensures information-theoretic security for the distribution of random bits between two remote parties. To extend QKD applications to fiber-to-the-home optical communications, such as gigabit-capable passive optical networks (GPONs), an effective method is the use of wavelength-division multiplexing. However, the Raman scattering noise from intensive classical traffic and the huge loss introduced by the beam splitter in a GPON severely limits the performance of QKD. Here, we demonstrate the integration of QKD and a commercial GPON system with fiber lengths up to 14 km, in which the maximum splitting ratio of the beam splitter reaches 1:64. By placing the QKD transmitter on the optical line terminal side, we reduce the Raman noise collected at the QKD receiver. Using a bypass structure, the loss of the beam splitter is circumvented effectively. Our results pave the way to extending the applications of QKD to last-mile communications.
Experimentally feasible security check for n-qubit quantum secret sharing
Schauer, Stefan; Huber, Marcus; Hiesmayr, Beatrix C.
2010-12-01
In this article we present a general security strategy for quantum secret sharing (QSS) protocols based on the scheme presented by Hillery, Bužek, and Berthiaume (HBB) [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.59.1829 59, 1829 (1999)]. We focus on a generalization of the HBB protocol to n communication parties thus including n-partite Greenberger-Horne-Zeilinger states. We show that the multipartite version of the HBB scheme is insecure in certain settings and impractical when going to large n. To provide security for such QSS schemes in general we use the framework presented by some of the authors [M. Huber, F. Mintert, A. Gabriel, B. C. Hiesmayr, Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.104.210501 104, 210501 (2010)] to detect certain genuine n-partite entanglement between the communication parties. In particular, we present a simple inequality which tests the security.
Verevkin, Sergey P; Emel'yanenko, Vladimir N; Varfolomeev, Mikhail A; Solomonov, Boris N; Zherikova, Kseniya V; Melkhanova, Svetlana V
2014-12-11
Temperature dependence of vapor pressures for 12 dihalogen-substituted benzenes (halogen = F, Cl, Br, I) was studied by the transpiration method, and molar vaporization or sublimation enthalpies were derived. These data together with results available in the literature were collected and checked for internal consistency using structure-property correlations. Gas-phase enthalpies of formation of dihalogen-substituted benzenes were calculated by using quantum-chemical methods. Evaluated vaporization enthalpies in combination with gas-phase enthalpies of formation were used for estimation liquid-phase enthalpies of formation of dihalogen-substituted benzenes. Pairwise interactions of halogens on the benzene ring were derived and used for development of simple group additivity procedures for estimation of vaporization enthalpies, gas-phase, and liquid-phase enthalpies of formation of dihalogen-substituted benzenes.
Directory of Open Access Journals (Sweden)
Hemant Bamoriya
2014-08-01
Full Text Available Current study focuses on examining consumers‟ beliefs and behavioral intentions towards QR Codes in marketing across different cultures such as India & USA. Study also examines select variables that moderate the relationship between beliefs and behavioral intentions. For this a scenario based experimental design was used. Findings suggest positive relationship between beliefs & behavioral intention and between culture & beliefs. Based on the empirical findings, study make important implications for the marketers so as to bring effectiveness in QR Code based marketing campaigns. Use of QR Codes in marketing is prevailing rapidly, however its effective integration in marketing mix remains mysterious as very little is known about consumers‟ beliefs and behavioral intentions towards it. Reason is that such academic research is practically non-existent, thus current study is of particular value.
Miska, P; Even, J; Bertru, N; Corre, A L; Dehaese, O
2002-01-01
An experimental and theoretical comparative study of InAs quantum dots grown on (001) and (113)B InP substrates is performed. The difference between the optical transitions in the dots on the two substrates is attributed to strain effects. The influence of the first InP capping layer is also studied.
Quantum chemical and experimental studies on polymorphism of antiviral drug Lamivudine
Ramkumaar, G. R.; Srinivasan, S.; Bhoopathy, T. J.; Gunasekaran, S.
2012-12-01
Lamivudine, is chemically known as [4-amino-1-[(2R,5S)-2-(hydroxymethyl)-1,3-oxathiolan-5-yl]-1,2-dihydropyrimidin-2-one], is an anti-HIV agent belonging to the class of the non-nucleoside inhibitors of the HIV-1 virus reverse transcriptase. Spectral characteristics of Lamivudine have been studied by methods of FTIR, NMR and quantum chemistry. The FTIR and spectra of Lamivudine was recorded in the regions 4000-400 cm-1. The thermal stability of Lamivudine was studied by the thermogravimetric analysis (TGA). The isotropic 13C-nuclear magnetic shielding constants of this compound were calculated by employing the direct implementation of the gauge including-atomic-orbital (GIAO) method at the HF and B3LYP density functional theory using 6-31G(d,p) basis set. The optimized molecular geometry, bond orders, harmonic vibrational spectrum of anhydrous and hydrated Lamivudine were calculated by restricted Hartree Fock and density functional B3LYP method with the 6-31G(d,p) basis set using Gaussian 03W program.
Pal, Rajat; Panigrahi, Swati; Bhattacharyya, Dhananjay; Chakraborti, Abhay Sankar
2013-08-01
Quercetin and several other bioflavonoids possess antioxidant property. These biomolecules can reduce the diabetic complications, but metabolize very easily in the body. Nanoparticle-mediated delivery of a flavonoid may further increase its efficacy. Gold nanoparticle is used by different groups as vehicle for drug delivery, as it is least toxic to human body. Prior to search for the enhanced efficacy, the gold nanoparticle-flavonoid complex should be prepared and well characterized. In this article, we report the interaction of gold nanoparticle with quercetin. The interaction is confirmed by different biophysical techniques, such as Scanning Electron Microscope (SEM), Circular Dichroism (CD), Fourier-Transform InfraRed (FT-IR) spectroscopy and Thermal Gravimetric Analysis (TGA) and cross checked by quantum chemical calculations. These studies indicate that gold clusters are covered by citrate groups, which are hydrogen bonded to the quercetin molecules in the complex. We have also provided evidences how capping is important in stabilizing the gold nanoparticle and further enhances its interaction with other molecules, such as drugs. Our finding also suggests that gold nanoparticle-quercetin complex can pass through the membranes of human red blood cells.
Gonzalez, E; Lino, J; Deriabina, A; Herrera, J N F; Poltev, V I
2013-01-01
To elucidate details of the DNA-water interactions we performed the calculations and systemaitic search for minima of interaction energy of the systems consisting of one of DNA bases and one or two water molecules. The results of calculations using two force fields of molecular mechanics (MM) and correlated ab initio method MP2/6-31G(d, p) of quantum mechanics (QM) have been compared with one another and with experimental data. The calculations demonstrated a qualitative agreement between geometry characteristics of the most of local energy minima obtained via different methods. The deepest minima revealed by MM and QM methods correspond to water molecule position between two neighbor hydrophilic centers of the base and to the formation by water molecule of hydrogen bonds with them. Nevertheless, the relative depth of some minima and peculiarities of mutual water-base positions in' these minima depend on the method used. The analysis revealed insignificance of some differences in the results of calculations performed via different methods and the importance of other ones for the description of DNA hydration. The calculations via MM methods enable us to reproduce quantitatively all the experimental data on the enthalpies of complex formation of single water molecule with the set of mono-, di-, and trimethylated bases, as well as on water molecule locations near base hydrophilic atoms in the crystals of DNA duplex fragments, while some of these data cannot be rationalized by QM calculations.
Rolando, A.
2006-01-01
In this paper the compression strength of a clay brickwork masonry bound with cement mortar is analyzed. The target is to obtain the characteristic compression strength of unreinforced brickwork masonry. This research try to test the validity of the analytical equations in European codes, comparing the experimental strength with the analytically obtained from the strength of its components (clay brick and cement mortar).En este artículo se analiza la resistencia a compresión de una ...
2016-09-01
collected ....................... 5 7. Experimentally measured noise figure and gain for several low- noise amplifiers , including COTF and cryogenically...frequency domain of the two cryogenically cooled low noise amplifiers in comparison with the ideal simulation when all the data is normalized...resonance). Both of these procedures require microwave and RF pulses, respectively, at various phase shifts, power , and duration to control the spin. An I/Q
Balázs, András
2006-08-01
A physical (affine Hilbert spaces) frame is developed for the discussion of the interdependence of the problem of the origin (symbolic assignment) of the genetic code and a possible endophysical (a kind of "internal") quantum measurement in an explicite way, following the general considerations of Balázs (Balázs, A., 2003. BioSystems 70, 43-54; Balázs, A., 2004a. BioSystems 73, 1-11). Using the Everett (a dynamic) interpretation of quantum mechanics, both the individual code assignment and the concatenated linear symbolism is discussed. It is concluded that there arises a skewed quantal probability field, with a natural dynamic non-linearity in codon assignment within the physical model adopted (essentially corresponding to a much discussed biochemical frame of self-catalyzed binding (charging) of t RNA like proto RNAs (ribozymes) with amino acids). This dynamic specific molecular complex assumption of individual code assignment, and the divergence of the code in relation to symbol concatenation, are discussed: our frame supports the former and interpret the latter as single-type codon (triplet), also unambiguous and extended assignment, selection in molecular evolution, corresponding to converging towards the fixedpoint of the internal dynamics of measurement, either in a protein- or RNA-world. In this respect, the general physical consequence is the introduction of a fourth rank semidiagonal energy tensor (see also Part II) ruling the internal dynamics as a non-linear in principle second-order one. It is inferred, as a summary, that if the problem under discussion could be expressed by the concepts of the Copenhagen interpretation of quantum mechanics in some yet not quite specified way, the matter would be particularly interesting with respect to both the origin of life and quantum mechanics, as a dynamically supported natural measurement-theoretical split between matter ("hardware") and (internal) symbolism ("software") aspects of living matter.
Gilbert, Gerald; Hamrick, Michael
2013-01-01
This book provides a detailed account of the theory and practice of quantum cryptography. Suitable as the basis for a course in the subject at the graduate level, it crosses the disciplines of physics, mathematics, computer science and engineering. The theoretical and experimental aspects of the subject are derived from first principles, and attention is devoted to the practical development of realistic quantum communications systems. The book also includes a comprehensive analysis of practical quantum cryptography systems implemented in actual physical environments via either free-space or fiber-optic cable quantum channels. This book will be a valuable resource for graduate students, as well as professional scientists and engineers, who desire an introduction to the field that will enable them to undertake research in quantum cryptography. It will also be a useful reference for researchers who are already active in the field, and for academic faculty members who are teaching courses in quantum information s...
An algorithm for minimization of quantum cost
Banerjee, Anindita; Pathak, Anirban
2009-01-01
A new algorithm for minimization of quantum cost of quantum circuits has been designed. The quantum cost of different quantum circuits of particular interest (eg. circuits for EPR, quantum teleportation, shor code and different quantum arithmetic operations) are computed by using the proposed algorithm. The quantum costs obtained using the proposed algorithm is compared with the existing results and it is found that the algorithm has produced minimum quantum cost in all cases.
Introduction to quantum information science
Energy Technology Data Exchange (ETDEWEB)
Hayashi, Masahito [Nagoya Univ. (Japan). Graduate School of Mathematics; Ishizaka, Satoshi [Hiroshima Univ., Higashi-Hiroshima (Japan). Graduate School of Integrated Arts and Sciences; Kawachi, Akinori [Tokyo Institute of Technology (Japan). Dept. of Mathematical and Computing Sciences; Kimura, Gen [Shibaura Institute of Technology, Saitama (Japan). College of Systems Engineering and Science; Ogawa, Tomohiro [Univ. of Electro-Communications, Tokyo (Japan). Graduate School of Information Systems
2015-04-01
Presents the mathematical foundation for quantum information in a very didactic way. Summarizes all required mathematical knowledge in linear algebra. Supports teaching and learning with more than 100 exercises with solutions. Includes brief descriptions to recent results with references. This book presents the basics of quantum information, e.g., foundation of quantum theory, quantum algorithms, quantum entanglement, quantum entropies, quantum coding, quantum error correction and quantum cryptography. The required knowledge is only elementary calculus and linear algebra. This way the book can be understood by undergraduate students. In order to study quantum information, one usually has to study the foundation of quantum theory. This book describes it from more an operational viewpoint which is suitable for quantum information while traditional textbooks of quantum theory lack this viewpoint. The current book bases on Shor's algorithm, Grover's algorithm, Deutsch-Jozsa's algorithm as basic algorithms. To treat several topics in quantum information, this book covers several kinds of information quantities in quantum systems including von Neumann entropy. The limits of several kinds of quantum information processing are given. As important quantum protocols,this book contains quantum teleportation, quantum dense coding, quantum data compression. In particular conversion theory of entanglement via local operation and classical communication are treated too. This theory provides the quantification of entanglement, which coincides with von Neumann entropy. The next part treats the quantum hypothesis testing. The decision problem of two candidates of the unknown state are given. The asymptotic performance of this problem is characterized by information quantities. Using this result, the optimal performance of classical information transmission via noisy quantum channel is derived. Quantum information transmission via noisy quantum channel by quantum error
Energy Technology Data Exchange (ETDEWEB)
Chang Oh
2005-09-01
The very high temperature gas-cooled reactors (VHTGRs) are those concepts that have average coolant temperatures above 9000C or operational fuel temperatures above 12500C. These concepts provide the potential for increased energy conversion efficiency and for high-temperature process heat application in addition to power generation and nuclear hydrogen generation. While all the High Temperature Gas Cooled Reactor (HTGR) concepts have sufficiently high temperatures to support process heat applications, such as desalination and cogeneration, the VHTGR’s higher temperatures are suitable for particular applications such as thermochemical hydrogen production. However, the high temperature operation can be detrimental to safety following a loss-of-coolant accident (LOCA) initiated by pipe breaks caused by seismic or other events. Following the loss of coolant through the break and coolant depressurization, air from the containment will enter the core by molecular diffusion and ultimately by natural convection, leading to oxidation of the in-core graphite structures and fuel. The oxidation will release heat and accelerate the heatup of the reactor core. Thus, without any effective countermeasures, a pipe break may lead to significant fuel damage and fission product release. The Idaho National Laboratory (INL) has investigated this event for the past three years for the HTGR. However, the computer codes used, and in fact none of the world’s computer codes, have been sufficiently developed and validated to reliably predict this event. New code development, improvement of the existing codes, and experimental validation are imperative to narrow the uncertainty in the predictions of this type of accident. The objectives of this Korean/United States collaboration are to develop advanced computational methods for VHTGR safety analysis codes and to validate these computer codes.
Experimental and quantum chemical studies of a novel synthetic prenylated chalcone
Directory of Open Access Journals (Sweden)
Espinoza-Hicks José C
2013-01-01
Full Text Available Abstract Background Chalcones are ubiquitous natural compounds with a wide variety of reported biological activities, including antitumoral, antiviral and antimicrobial effects. Furthermore, chalcones are being studied for its potential use in organic electroluminescent devices; therefore the description of their spectroscopic properties is important to elucidate the structure of these molecules. One of the main techniques available for structure elucidation is the use of Nuclear Magnetic Resonance Spectroscopy (NMR. Accordingly, the prediction of the NMR spectra in this kind of molecules is necessary to gather information about the influence of substituents on their spectra. Results A novel substituted chalcone has been synthetized. In order to identify the functional groups present in the new synthesized compound and confirm its chemical structure, experimental and theoretical 1H-NMR and 13C-NMR spectra were analyzed. The theoretical molecular structure and NMR spectra were calculated at both the Hartree-Fock and Density Functional (meta: TPSS; hybrid: B3LYP and PBE1PBE; hybrid meta GGA: M05-2X and M06-2X levels of theory in combination with a 6-311++G(d,p basis set. The structural parameters showed that the best method for geometry optimization was DFT:M06-2X/6-311++G(d,p, whereas the calculated bond angles and bond distances match experimental values of similar chalcone derivatives. The NMR calculations were carried out using the Gauge-Independent Atomic Orbital (GIAO formalism in a DFT:M06-2X/6-311++G(d,p optimized geometry. Conclusion Considering all HF and DFT methods with GIAO calculations, TPSS and PBE1PBE were the most accurate methods used for calculation of 1H-NMR and 13C-NMR chemical shifts, which was almost similar to the B3LYP functional, followed in order by HF, M05-2X and M06-2X methods. All calculations were done using the Gaussian 09 software package. Theoretical calculations can be used to predict and confirm the structure of
Brahmachari, Goutam; Mondal, Avijit; Nayek, Nayana; Kumar, Abhishek; Srivastava, Ambrish Kumar; Misra, Neeraj
2017-09-01
Poriferasterol, a biologically relevant phytosterol, has been isolated and identified first-time from Cassia sophera Linn. (family: Caesalpiniaceae) based on detailed spectral studies. Exhaustive theoretical studies on the molecular structure, vibrational spectra, HOMO, LUMO, MESP surfaces and reactivity descriptor of this plant-derived natural molecule have been performed. The experimentally observed FT-IR spectrum of the title compound has been compared with spectral data obtained by DFT-B3LYP/6-311 + G (d,p) method. The UV-visible spectrum of the title compound has also been recorded and the electronic properties, such as frontier orbitals and band gap energy are measured by TD-DFT approach. The 1H and 13C NMR spectrum has been calculated by using the gauge independent atomic orbital method and compared with the observed data.
Efficient quantum walk on a quantum processor
Qiang, Xiaogang; Loke, Thomas; Montanaro, Ashley; Aungskunsiri, Kanin; Zhou, Xiaoqi; O'Brien, Jeremy L.; Wang, Jingbo B.; Matthews, Jonathan C. F.
2016-01-01
The random walk formalism is used across a wide range of applications, from modelling share prices to predicting population genetics. Likewise, quantum walks have shown much potential as a framework for developing new quantum algorithms. Here we present explicit efficient quantum circuits for implementing continuous-time quantum walks on the circulant class of graphs. These circuits allow us to sample from the output probability distributions of quantum walks on circulant graphs efficiently. We also show that solving the same sampling problem for arbitrary circulant quantum circuits is intractable for a classical computer, assuming conjectures from computational complexity theory. This is a new link between continuous-time quantum walks and computational complexity theory and it indicates a family of tasks that could ultimately demonstrate quantum supremacy over classical computers. As a proof of principle, we experimentally implement the proposed quantum circuit on an example circulant graph using a two-qubit photonics quantum processor. PMID:27146471
Efficient quantum walk on a quantum processor.
Qiang, Xiaogang; Loke, Thomas; Montanaro, Ashley; Aungskunsiri, Kanin; Zhou, Xiaoqi; O'Brien, Jeremy L; Wang, Jingbo B; Matthews, Jonathan C F
2016-05-05
The random walk formalism is used across a wide range of applications, from modelling share prices to predicting population genetics. Likewise, quantum walks have shown much potential as a framework for developing new quantum algorithms. Here we present explicit efficient quantum circuits for implementing continuous-time quantum walks on the circulant class of graphs. These circuits allow us to sample from the output probability distributions of quantum walks on circulant graphs efficiently. We also show that solving the same sampling problem for arbitrary circulant quantum circuits is intractable for a classical computer, assuming conjectures from computational complexity theory. This is a new link between continuous-time quantum walks and computational complexity theory and it indicates a family of tasks that could ultimately demonstrate quantum supremacy over classical computers. As a proof of principle, we experimentally implement the proposed quantum circuit on an example circulant graph using a two-qubit photonics quantum processor.
Quantum proofs for classical theorems
Drucker, A.; de Wolf, R.
2011-01-01
Alongside the development of quantum algorithms and quantum complexity theory in recent years, quantum techniques have also proved instrumental in obtaining results in diverse classical (non-quantum) areas, such as coding theory, communication complexity, and polynomial approximations. In this paper
Directory of Open Access Journals (Sweden)
Frisoni Manuela
2016-01-01
Full Text Available ANITA-2000 is a code package for the activation characterization of materials exposed to neutron irradiation released by ENEA to OECD-NEADB and ORNL-RSICC. The main component of the package is the activation code ANITA-4M that computes the radioactive inventory of a material exposed to neutron irradiation. The code requires the decay data library (file fl1 containing the quantities describing the decay properties of the unstable nuclides and the library (file fl2 containing the gamma ray spectra emitted by the radioactive nuclei. The fl1 and fl2 files of the ANITA-2000 code package, originally based on the evaluated nuclear data library FENDL/D-2.0, were recently updated on the basis of the JEFF-3.1.1 Radioactive Decay Data Library. This paper presents the results of the validation of the new fl1 decay data library through the comparison of the ANITA-4M calculated values with the measured electron and photon decay heats and activities of fusion material samples irradiated at the 14 MeV Frascati Neutron Generator (FNG of the NEA-Frascati Research Centre. Twelve material samples were considered, namely: Mo, Cu, Hf, Mg, Ni, Cd, Sn, Re, Ti, W, Ag and Al. The ratios between calculated and experimental values (C/E are shown and discussed in this paper.
Energy Technology Data Exchange (ETDEWEB)
Romero, L.; Travesi, A.
1983-07-01
The REX code, written in Fortran IV, performs the fitting a set of experimental data to different kind of functions as: straight-line (Y = A + BX) , and various exponential type (Y-A B{sup x}, Y=A X{sup B}; Y=A exp(BX) ) , using the Least Squares criterion. Such fitting could be done directly for one selected function of for the our simultaneously and allows to chose the function that best fitting to the data, since presents the statistics data of all the fitting. Further, it presents the graphics plotting, of the fitted function, in the appropriate coordinate axes system. An additional option allows also the Graphic plotting of experimental data used for the fitting. All the data necessary to execute this code are asked to the operator in the terminal screen, in the iterative way by screen-operator dialogue, and the values are introduced through the keyboard. This code could be executed with any computer provided with graphic screen and keyboard terminal, with a X-Y plotter serial connected to the graphics terminal. (Author) 5 refs.
Using a quantum computer to investigate quantum chaos
Schack, Ruediger
1997-01-01
We show that the quantum baker's map, a prototypical map invented for theoretical studies of quantum chaos, has a very simple realization in terms of quantum gates. Chaos in the quantum baker's map could be investigated experimentally on a quantum computer based on only 3 qubits.
Directory of Open Access Journals (Sweden)
John F. Moxnes
2014-06-01
Full Text Available There has been increasing interest in numerical simulations of fragmentation of expanding warheads in 3D. Accordingly there is a pressure on developers of leading commercial codes, such as LS-DYNA, AUTODYN and IMPETUS Afea, to implement the reliable fracture models and the efficient solution techniques. The applicability of the Johnson–Cook strength and fracture model is evaluated by comparing the fracture behaviour of an expanding steel casing of a warhead with experiments. The numerical codes and different numerical solution techniques, such as Eulerian, Lagrangian, Smooth particle hydrodynamics (SPH, and the corpuscular models recently implemented in IMPETUS Afea are compared. For the same solution techniques and material models we find that the codes give similar results. The SPH technique and the corpuscular technique are superior to the Eulerian technique and the Lagrangian technique (with erosion when it is applied to materials that have fluid like behaviour such as the explosive and the tracer. The Eulerian technique gives much larger calculation time and both the Lagrangian and Eulerian techniques seem to give less agreement with our measurements. To more correctly simulate the fracture behaviours of the expanding steel casing, we applied that ductility decreases with strain rate. The phenomena may be explained by the realization of adiabatic shear bands. An implemented node splitting algorithm in IMPETUS Afea seems very promising.
A combined experimental (IR, Raman and UV-Vis) and quantum chemical study of canadine
Joshi, Bhawani Datt; Srivastava, Anubha; Tandon, Poonam; Jain, Sudha; Ayala, A. P.
2018-02-01
Plant based natural products cover a major sector of the medicinal field, as such focus on plant research has been increased all over the world. As an attempt to aid that research, we have performed structural and spectroscopic analysis of a natural product, an alkaloid: canadine. Both ab initio Hartree-Fock (HF) and density functional theory (DFT) employing B3LYP using 6-311 ++G(d,p) basis set were used for the calculations. The calculated vibrational frequencies were scaled and compared with the experimental infrared and Raman spectra. The complete vibrational assignments were made using potential energy distribution. The structure-activity relation has also been interpreted by mapping electrostatic potential surface and evaluating the reactivity descriptors, which are valuable information for quality control of medicines and drug-receptor interactions. Natural bond orbital analysis has also been performed to understand the stability and hyperconjugative interactions of the molecule. Furthermore, UV-Vis spectra have been recorded in an ethanol solvent (EtOH) and the electronic property has been analyzed employing TD-DFT for both gaseous and solvent phase. The HOMO and LUMO calculation with their energy gap show that charge transfer occurs within the molecule. Additionally, the nonlinear optical properties of the title compound have been interpreted that predicts it's the best candidate for the NLO materials.
A high repetition rate experimental setup for quantum non-linear optics with cold Rydberg atoms
Busche, Hannes; Ball, Simon W.; Huillery, Paul
2016-12-01
Using electromagnetically induced transparency and photon storage, the strong dipolar interactions between Rydberg atoms and the resulting dipole blockade can be mapped onto light fields to realise optical non-linearities and interactions at the single photon level. We report on the realisation of an experimental apparatus designed to study interactions between single photons stored as Rydberg excitations in optically trapped microscopic ensembles of ultracold 87Rb atoms. A pair of in-vacuum high numerical aperture lenses focus excitation and trapping beams down to 1 μm, well below the Rydberg blockade. Thanks to efficient magneto-optical trap (MOT) loading from an atomic beam generated by a 2D MOT and the ability to recycle the microscopic ensembles more than 20000 times without significant atom loss, we achieve effective repetition rates exceeding 110 kHz to obtain good photon counting statistics on reasonable time scales. To demonstrate the functionality of the setup, we present evidence of strong photon interactions including saturation of photon storage and the retrieval of non-classical light. Using in-vacuum antennae operating at up to 40 GHz, we perform microwave spectroscopy on photons stored as Rydberg excitations and observe an interaction induced change in lineshape depending on the number of stored photons.
Quantum information causality.
Pitalúa-García, Damián
2013-05-24
How much information can a transmitted physical system fundamentally communicate? We introduce the principle of quantum information causality, which states the maximum amount of quantum information that a quantum system can communicate as a function of its dimension, independently of any previously shared quantum physical resources. We present a new quantum information task, whose success probability is upper bounded by the new principle, and show that an optimal strategy to perform it combines the quantum teleportation and superdense coding protocols with a task that has classical inputs.
Quantum information and coherence
Öhberg, Patrik
2014-01-01
This book offers an introduction to ten key topics in quantum information science and quantum coherent phenomena, aimed at graduate-student level. The chapters cover some of the most recent developments in this dynamic research field where theoretical and experimental physics, combined with computer science, provide a fascinating arena for groundbreaking new concepts in information processing. The book addresses both the theoretical and experimental aspects of the subject, and clearly demonstrates how progress in experimental techniques has stimulated a great deal of theoretical effort and vice versa. Experiments are shifting from simply preparing and measuring quantum states to controlling and manipulating them, and the book outlines how the first real applications, notably quantum key distribution for secure communication, are starting to emerge. The chapters cover quantum retrodiction, ultracold quantum gases in optical lattices, optomechanics, quantum algorithms, quantum key distribution, quantum cont...
Layered Architecture for Quantum Computing
National Research Council Canada - National Science Library
Jones, N. Cody; Van Meter, Rodney; Fowler, Austin G; McMahon, Peter L; Kim, Jungsang; Ladd, Thaddeus D; Yamamoto, Yoshihisa
2012-01-01
.... We discuss many of the prominent techniques for implementing circuit-model quantum computing and introduce several new methods, with an emphasis on employing surface-code quantum error correction...
Quantum information theory mathematical foundation
Hayashi, Masahito
2017-01-01
This graduate textbook provides a unified view of quantum information theory. Clearly explaining the necessary mathematical basis, it merges key topics from both information-theoretic and quantum- mechanical viewpoints and provides lucid explanations of the basic results. Thanks to this unified approach, it makes accessible such advanced topics in quantum communication as quantum teleportation, superdense coding, quantum state transmission (quantum error-correction) and quantum encryption. Since the publication of the preceding book Quantum Information: An Introduction, there have been tremendous strides in the field of quantum information. In particular, the following topics – all of which are addressed here – made seen major advances: quantum state discrimination, quantum channel capacity, bipartite and multipartite entanglement, security analysis on quantum communication, reverse Shannon theorem and uncertainty relation. With regard to the analysis of quantum security, the present book employs an impro...
Directory of Open Access Journals (Sweden)
Mohammed Koubiti
2014-07-01
Full Text Available Various codes of line-shape modeling are compared to each other through the profile of the C ii 723-nm line for typical plasma conditions encountered in the ablation clouds of carbon pellets, injected in magnetic fusion devices. Calculations were performed for a single electron density of 1017 cm−3 and two plasma temperatures (T = 2 and 4 eV. Ion and electron temperatures were assumed to be equal (Te = Ti = T. The magnetic field, B, was set equal to either to zero or 4 T. Comparisons between the line-shape modeling codes and two experimental spectra of the C ii 723-nm line, measured perpendicularly to the B-field in the Large Helical Device (LHD using linear polarizers, are also discussed.
Quantum photonic network and physical layer security.
Sasaki, Masahide; Endo, Hiroyuki; Fujiwara, Mikio; Kitamura, Mitsuo; Ito, Toshiyuki; Shimizu, Ryosuke; Toyoshima, Morio
2017-08-06
Quantum communication and quantum cryptography are expected to enhance the transmission rate and the security (confidentiality of data transmission), respectively. We study a new scheme which can potentially bridge an intermediate region covered by these two schemes, which is referred to as quantum photonic network. The basic framework is information theoretically secure communications in a free space optical (FSO) wiretap channel, in which an eavesdropper has physically limited access to the main channel between the legitimate sender and receiver. We first review a theoretical framework to quantify the optimal balance of the transmission efficiency and the security level under power constraint and at finite code length. We then present experimental results on channel characterization based on 10 MHz on-off keying transmission in a 7.8 km terrestrial FSO wiretap channel.This article is part of the themed issue 'Quantum technology for the 21st century'. © 2017 The Author(s).
Quantum photonic network and physical layer security
Sasaki, Masahide; Endo, Hiroyuki; Fujiwara, Mikio; Kitamura, Mitsuo; Ito, Toshiyuki; Shimizu, Ryosuke; Toyoshima, Morio
2017-06-01
Quantum communication and quantum cryptography are expected to enhance the transmission rate and the security (confidentiality of data transmission), respectively. We study a new scheme which can potentially bridge an intermediate region covered by these two schemes, which is referred to as quantum photonic network. The basic framework is information theoretically secure communications in a free space optical (FSO) wiretap channel, in which an eavesdropper has physically limited access to the main channel between the legitimate sender and receiver. We first review a theoretical framework to quantify the optimal balance of the transmission efficiency and the security level under power constraint and at finite code length. We then present experimental results on channel characterization based on 10 MHz on-off keying transmission in a 7.8 km terrestrial FSO wiretap channel. This article is part of the themed issue 'Quantum technology for the 21st century'.
Al-Otaibi, Jamelah S.; Teesdale Spittle, Paul; El Gogary, Tarek M.
2017-01-01
Anthraquinones form the basis of several anticancer drugs. Anthraquinones anticancer drugs carry out their cytotoxic activities through their interaction with DNA, and inhibition of topoisomerase II activity. Anthraquinones (AQ4 and AQ4H) were synthesized and studied along with 1,4-DAAQ by computational and experimental tools. The purpose of this study is to shade more light on mechanism of interaction between anthraquinone DNA affinic agents and different types of DNA. This study will lead to gain of information useful for drug design and development. Molecular structures were optimized using DFT B3LYP/6-31 + G(d). Depending on intramolecular hydrogen bonding interactions two conformers of AQ4 were detected and computed as 25.667 kcal/mol apart. Molecular reactivity of the anthraquinone compounds was explored using global and condensed descriptors (electrophilicity and Fukui functions). Molecular docking studies for the inhibition of CDK2 and DNA binding were carried out to explore the anti cancer potency of these drugs. NMR and UV-VIS electronic absorption spectra of anthraquinones/DNA were investigated at the physiological pH. The interaction of the three anthraquinones (AQ4, AQ4H and 1,4-DAAQ) were studied with three DNA (calf thymus DNA, (Poly[dA].Poly[dT]) and (Poly[dG].Poly[dC]). NMR study shows a qualitative pattern of drug/DNA interaction in terms of band shift and broadening. UV-VIS electronic absorption spectra were employed to measure the affinity constants of drug/DNA binding using Scatchard analysis.
Quantum Optics with Quantum Dots in Photonic Nanowires
DEFF Research Database (Denmark)
Gérard, J. M.; Claudon, J.; Bleuse, J.
2012-01-01
We review recent experimental and theoretical results, which highlight the strong interest of the photonic wire geometry for solid-state quantum optics and quantum optoelectronic devices.......We review recent experimental and theoretical results, which highlight the strong interest of the photonic wire geometry for solid-state quantum optics and quantum optoelectronic devices....
Energy Technology Data Exchange (ETDEWEB)
Berthoud, G.; Crecy, F. de; Meignen, R.; Valette, M. [CEA-G, DRN/DTP/SMTH, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France)
1998-01-01
The premixing phase of a molten fuel-coolant interaction is studied by the way of mechanistic multidimensional calculation. Beside water and steam, corium droplet flow and continuous corium jet flow are calculated independent. The 4-field MC3D code and a detailed hot jet fragmentation model are presented. MC3D calculations are compared to the FARO L14 experiment results and are found to give satisfactory results; heat transfer and jet fragmentation models are still to be improved to predict better final debris size values. (author)
DEFF Research Database (Denmark)
Yu, Xianbin; Gibbon, Timothy Braidwood; Tafur Monroy, Idelfonso
2009-01-01
the requirements of Federal Communications Commission regulations. We experimentally demonstrated a 781.25-Mb/s UWB-over-fiber transmission system. A digital-signal-processing-based receiver is employed to calculate the bit-error rate. Our proposed system has potential application in future high-speed UWB impulse......In this letter, an all-optical incoherent scheme for generation of binary phase-coded ultra-wideband (UWB) impulse radio signals is proposed. The generated UWB pulses utilize relaxation oscillations of an optically injected distributed feedback laser that are binary phase encoded (0 and ) and meet...
Fomin, Vladimir M
2013-01-01
This book deals with a new class of materials, quantum rings. Innovative recent advances in experimental and theoretical physics of quantum rings are based on the most advanced state-of-the-art fabrication and characterization techniques as well as theoretical methods. The experimental efforts allow to obtain a new class of semiconductor quantum rings formed by capping self-organized quantum dots grown by molecular beam epitaxy. Novel optical and magnetic properties of quantum rings are associated with non-trivial topologies at the nanoscale. An adequate characterization of quantum rings is po
Quantum computational supremacy
Harrow, Aram W.; Montanaro, Ashley
2017-09-01
The field of quantum algorithms aims to find ways to speed up the solution of computational problems by using a quantum computer. A key milestone in this field will be when a universal quantum computer performs a computational task that is beyond the capability of any classical computer, an event known as quantum supremacy. This would be easier to achieve experimentally than full-scale quantum computing, but involves new theoretical challenges. Here we present the leading proposals to achieve quantum supremacy, and discuss how we can reliably compare the power of a classical computer to the power of a quantum computer.
A new QMD code for heavy-ion collisions
Kim, Kyungil; Kim, Youngman; Lee, Kang Seog
2017-11-01
We develop a new quantum molecular dynamics (QMD) type nuclear transport code to simulate heavy-ion collisions for RAON, a new accelerator complex under construction in Korea. At RAON, the rare isotope beams with energies from a few MeV/n to a few hundreds MeV/n will be utilized. QMD is one of the widely used theoretical methods and is useful for both theoretical and experimental purposes. We describe our QMD model with the numerical realization. The validity of the code is tested by comparing our simulation results with experimental data and also results from other transport codes in 197Au+197Au collisions at Elab = 90 - 120 MeV/n. Finally, we present a brief discussion on applicability and outlook of our code.
Five-wave-packet quantum error correction based on continuous-variable cluster entanglement.
Hao, Shuhong; Su, Xiaolong; Tian, Caixing; Xie, Changde; Peng, Kunchi
2015-10-26
Quantum error correction protects the quantum state against noise and decoherence in quantum communication and quantum computation, which enables one to perform fault-torrent quantum information processing. We experimentally demonstrate a quantum error correction scheme with a five-wave-packet code against a single stochastic error, the original theoretical model of which was firstly proposed by S. L. Braunstein and T. A. Walker. Five submodes of a continuous variable cluster entangled state of light are used for five encoding channels. Especially, in our encoding scheme the information of the input state is only distributed on three of the five channels and thus any error appearing in the remained two channels never affects the output state, i.e. the output quantum state is immune from the error in the two channels. The stochastic error on a single channel is corrected for both vacuum and squeezed input states and the achieved fidelities of the output states are beyond the corresponding classical limit.
Quantum Secure Direct Communication with Quantum Memory.
Zhang, Wei; Ding, Dong-Sheng; Sheng, Yu-Bo; Zhou, Lan; Shi, Bao-Sen; Guo, Guang-Can
2017-06-02
Quantum communication provides an absolute security advantage, and it has been widely developed over the past 30 years. As an important branch of quantum communication, quantum secure direct communication (QSDC) promotes high security and instantaneousness in communication through directly transmitting messages over a quantum channel. The full implementation of a quantum protocol always requires the ability to control the transfer of a message effectively in the time domain; thus, it is essential to combine QSDC with quantum memory to accomplish the communication task. In this Letter, we report the experimental demonstration of QSDC with state-of-the-art atomic quantum memory for the first time in principle. We use the polarization degrees of freedom of photons as the information carrier, and the fidelity of entanglement decoding is verified as approximately 90%. Our work completes a fundamental step toward practical QSDC and demonstrates a potential application for long-distance quantum communication in a quantum network.
Quantum Secure Direct Communication with Quantum Memory
Zhang, Wei; Ding, Dong-Sheng; Sheng, Yu-Bo; Zhou, Lan; Shi, Bao-Sen; Guo, Guang-Can
2017-06-01
Quantum communication provides an absolute security advantage, and it has been widely developed over the past 30 years. As an important branch of quantum communication, quantum secure direct communication (QSDC) promotes high security and instantaneousness in communication through directly transmitting messages over a quantum channel. The full implementation of a quantum protocol always requires the ability to control the transfer of a message effectively in the time domain; thus, it is essential to combine QSDC with quantum memory to accomplish the communication task. In this Letter, we report the experimental demonstration of QSDC with state-of-the-art atomic quantum memory for the first time in principle. We use the polarization degrees of freedom of photons as the information carrier, and the fidelity of entanglement decoding is verified as approximately 90%. Our work completes a fundamental step toward practical QSDC and demonstrates a potential application for long-distance quantum communication in a quantum network.
Steffen, Matthias
Solving computational problems require resources such as time, memory, and space. In the classical model of computation, computational complexity theory has categorized problems according to how difficult it is to solve them as the problem size increases. Remarkably, a quantum computer could solve certain problems using fundamentally fewer resources compared to a conventional computer, and therefore has garnered significant attention. Yet because of the delicate nature of entangled quantum states, the construction of a quantum computer poses an enormous challenge for experimental and theoretical scientists across multi-disciplinary areas including physics, engineering, materials science, and mathematics. While the field of quantum computing still has a long way to grow before reaching full maturity, state-of-the-art experiments on the order of 10 qubits are beginning to reach a fascinating stage at which they can no longer be emulated using even the fastest supercomputer. This raises the hope that small quantum computer demonstrations could be capable of approximately simulating or solving problems that also have practical applications. In this talk I will review the concepts behind quantum computing, and focus on the status of superconducting qubits which includes steps towards quantum error correction and quantum simulations.
Approximate Quantum Adders with Genetic Algorithms: An IBM Quantum Experience
Directory of Open Access Journals (Sweden)
Li Rui
2017-07-01
Full Text Available It has been proven that quantum adders are forbidden by the laws of quantum mechanics. We analyze theoretical proposals for the implementation of approximate quantum adders and optimize them by means of genetic algorithms, improving previous protocols in terms of efficiency and fidelity. Furthermore, we experimentally realize a suitable approximate quantum adder with the cloud quantum computing facilities provided by IBM Quantum Experience. The development of approximate quantum adders enhances the toolbox of quantum information protocols, paving the way for novel applications in quantum technologies.
Approximate Quantum Adders with Genetic Algorithms: An IBM Quantum Experience
Li, Rui; Alvarez-Rodriguez, Unai; Lamata, Lucas; Solano, Enrique
2017-07-01
It has been proven that quantum adders are forbidden by the laws of quantum mechanics. We analyze theoretical proposals for the implementation of approximate quantum adders and optimize them by means of genetic algorithms, improving previous protocols in terms of efficiency and fidelity. Furthermore, we experimentally realize a suitable approximate quantum adder with the cloud quantum computing facilities provided by IBM Quantum Experience. The development of approximate quantum adders enhances the toolbox of quantum information protocols, paving the way for novel applications in quantum technologies.
Fault-tolerant interface between quantum memories and quantum processors.
Poulsen Nautrup, Hendrik; Friis, Nicolai; Briegel, Hans J
2017-11-06
Topological error correction codes are promising candidates to protect quantum computations from the deteriorating effects of noise. While some codes provide high noise thresholds suitable for robust quantum memories, others allow straightforward gate implementation needed for data processing. To exploit the particular advantages of different topological codes for fault-tolerant quantum computation, it is necessary to be able to switch between them. Here we propose a practical solution, subsystem lattice surgery, which requires only two-body nearest-neighbor interactions in a fixed layout in addition to the indispensable error correction. This method can be used for the fault-tolerant transfer of quantum information between arbitrary topological subsystem codes in two dimensions and beyond. In particular, it can be employed to create a simple interface, a quantum bus, between noise resilient surface code memories and flexible color code processors.
Energy Technology Data Exchange (ETDEWEB)
Meloni, P. [ENEA, Bologna (Italy); D' Auria, F.; Oriolo, F. [Pisa Univ. (Italy). Dipt. di Costruzioni Meccaniche e Nucleari; Dell' Orco, G.; Polazzi, G. [ENEA, Brasimone (Italy)
1998-07-01
Within the frame of the European Fusion Technology Programme, the HE-FUS3 helium facility was selected for the execution of thermal-hydraulic experimental campaigns on the HCPB Blanket mock-ups. The studies for the DEMO HCPB Blanket design, for the 1997-1998, contemplates a task concerning the Out-of-Pile tests for the HCPB Test Blanket Module (TBM). One of the main objectives of the task is the qualification of the HE-FUS3 capability to perform tests both in normal and off-normal conditions. (authors)
Energy Technology Data Exchange (ETDEWEB)
Chang Oh
2006-03-01
The very high-temperature gas-cooled reactor (VHTR) is envisioned as a single- or dual-purpose reactor for electricity and hydrogen generation. The concept has average coolant temperatures above 9000C and operational fuel temperatures above 12500C. The concept provides the potential for increased energy conversion efficiency and for high-temperature process heat application in addition to power generation. While all the High Temperature Gas Cooled Reactor (HTGR) concepts have sufficiently high temperature to support process heat applications, such as coal gasification, desalination or cogenerative processes, the VHTR’s higher temperatures allow broader applications, including thermochemical hydrogen production. However, the very high temperatures of this reactor concept can be detrimental to safety if a loss-of-coolant accident (LOCA) occurs. Following the loss of coolant through the break and coolant depressurization, air will enter the core through the break by molecular diffusion and ultimately by natural convection, leading to oxidation of the in-core graphite structure and fuel. The oxidation will accelerate heatup of the reactor core and the release of toxic gasses (CO and CO2) and fission products. Thus, without any effective countermeasures, a pipe break may lead to significant fuel damage and fission product release. Prior to the start of this Korean/United States collaboration, no computer codes were available that had been sufficiently developed and validated to reliably simulate a LOCA in the VHTR. Therefore, we have worked for the past three years on developing and validating advanced computational methods for simulating LOCAs in a VHTR. Research Objectives As described above, a pipe break may lead to significant fuel damage and fission product release in the VHTR. The objectives of this Korean/United States collaboration were to develop and validate advanced computational methods for VHTR safety analysis. The methods that have been developed are now
Podt, M.; Weenink, J.; Weenink, J.; Flokstra, Jakob; Rogalla, Horst
2001-01-01
We report on a superconducting quantum interference device (SQUID) system to read out large arrays of cryogenic detectors. In order to reduce the number of SQUIDs required for an array of these detectors, we used code-division multiplexing. This simplifies the electronics because of a significantly
Directory of Open Access Journals (Sweden)
Kaludov Nikola
2011-09-01
Full Text Available Abstract Background Developing resistance towards existing anti-malarial therapies emphasize the urgent need for new therapeutic options. Additionally, many malaria drugs in use today have high toxicity and low therapeutic indices. Gradient Biomodeling, LLC has developed a quantum-model search technology that uses quantum similarity and does not depend explicitly on chemical structure, as molecules are rigorously described in fundamental quantum attributes related to individual pharmacological properties. Therapeutic activity, as well as toxicity and other essential properties can be analysed and optimized simultaneously, independently of one another. Such methodology is suitable for a search of novel, non-toxic, active anti-malarial compounds. Methods A set of innovative algorithms is used for the fast calculation and interpretation of electron-density attributes of molecular structures at the quantum level for rapid discovery of prospective pharmaceuticals. Potency and efficacy, as well as additional physicochemical, metabolic, pharmacokinetic, safety, permeability and other properties were characterized by the procedure. Once quantum models are developed and experimentally validated, the methodology provides a straightforward implementation for lead discovery, compound optimizzation and de novo molecular design. Results Starting with a diverse training set of 26 well-known anti-malarial agents combined with 1730 moderately active and inactive molecules, novel compounds that have strong anti-malarial activity, low cytotoxicity and structural dissimilarity from the training set were discovered and experimentally validated. Twelve compounds were identified in silico and tested in vitro; eight of them showed anti-malarial activity (IC50 ≤ 10 μM, with six being very effective (IC50 ≤ 1 μM, and four exhibiting low nanomolar potency. The most active compounds were also tested for mammalian cytotoxicity and found to be non-toxic, with a
Chen, Geng; Zou, Yang; Zhang, Wen-Hao; Zhang, Zi-Huai; Zhou, Zong-Quan; He, De-Yong; Tang, Jian-Shun; Liu, Bi-Heng; Yu, Ying; Zha, Guo-Wei; Ni, Hai-Qiao; Niu, Zhi-Chuan; Han, Yong-Jian; Li, Chuan-Feng; Guo, Guang-Can
2016-05-26
Quantum emitters generating individual entangled photon pairs (IEPP) have significant fundamental advantages over schemes that suffer from multiple photon emission, or schemes that require post-selection techniques or the use of photon-number discriminating detectors. Quantum dots embedded within nanowires (QD-NWs) represent one of the most promising candidate for quantum emitters that provide a high collection efficiency of photons. However, a quantum emitter that generates IEPP in the telecom band is still an issue demanding a prompt solution. Here, we demonstrate in principle that IEPPs in the telecom band can be created by combining a single QD-NW and a nonlinear crystal waveguide. The QD-NW system serves as the single photon source, and the emitted visible single photons are split into IEPPs at approximately 1.55 μm through the process of spontaneous parametric down conversion (SPDC) in a periodically poled lithium niobate (PPLN) waveguide. The compatibility of the QD-PPLN interface is the determinant factor in constructing this novel hybrid-quantum-emitter (HQE). Benefiting from the desirable optical properties of QD-NWs and the extremely high nonlinear conversion efficiency of PPLN waveguides, we successfully generate IEPPs in the telecom band with the polarization degree of freedom. The entanglement of the generated photon pairs is confirmed by the entanglement witness. Our experiment paves the way to producing HQEs inheriting the advantages of multiple systems.
Quantum Error Correction Protects Quantum Search Algorithms Against Decoherence
Botsinis, Panagiotis; Babar, Zunaira; Alanis, Dimitrios; Chandra, Daryus; Nguyen, Hung; Ng, Soon Xin; Hanzo, Lajos
2016-01-01
When quantum computing becomes a wide-spread commercial reality, Quantum Search Algorithms (QSA) and especially Grover’s QSA will inevitably be one of their main applications, constituting their cornerstone. Most of the literature assumes that the quantum circuits are free from decoherence. Practically, decoherence will remain unavoidable as is the Gaussian noise of classic circuits imposed by the Brownian motion of electrons, hence it may have to be mitigated. In this contribution, we investigate the effect of quantum noise on the performance of QSAs, in terms of their success probability as a function of the database size to be searched, when decoherence is modelled by depolarizing channels’ deleterious effects imposed on the quantum gates. Moreover, we employ quantum error correction codes for limiting the effects of quantum noise and for correcting quantum flips. More specifically, we demonstrate that, when we search for a single solution in a database having 4096 entries using Grover’s QSA at an aggressive depolarizing probability of 10−3, the success probability of the search is 0.22 when no quantum coding is used, which is improved to 0.96 when Steane’s quantum error correction code is employed. Finally, apart from Steane’s code, the employment of Quantum Bose-Chaudhuri-Hocquenghem (QBCH) codes is also considered. PMID:27924865
Dür, Wolfgang; Lamprecht, Raphael; Heusler, Stefan
2017-07-01
A long-range quantum communication network is among the most promising applications of emerging quantum technologies. We discuss the potential of such a quantum internet for the secure transmission of classical and quantum information, as well as theoretical and experimental approaches and recent advances to realize them. We illustrate the involved concepts such as error correction, teleportation or quantum repeaters and consider an approach to this topic based on catchy visualizations as a context-based, modern treatment of quantum theory at high school.
Scaffold: Quantum Programming Language
2012-07-24
modules that the pro- grammer specifies using purely classical data, but calls with appropriately sized quantum registers as inputs. Tools within our...set of gates. Then line 2 is where the main module begins. Every free -standing program must contain 5 Gate Prototypes Module (classical/quantum code...definitions and example usages, and emphasizes the distinctions between classical and quantum data and operations. We discuss the context of the
Ficek, Zbigniew
2017-01-01
This book covers the main ideas, methods, and recent developments of quantum-limit optical spectroscopy and applications to quantum information, resolution spectroscopy, measurements beyond quantum limits, measurement of decoherence, and entanglement. Quantum-limit spectroscopy lies at the frontier of current experimental and theoretical techniques, and is one of the areas of atomic spectroscopy where the quantization of the field is essential to predict and interpret the existing experimental results. Currently, there is an increasing interest in quantum and precision spectroscopy both theoretically and experimentally, due to significant progress in trapping and cooling of single atoms and ions. This progress allows one to explore in the most intimate detail the ways in which light interacts with atoms and to measure spectral properties and quantum effects with high precision. Moreover, it allows one to perform subtle tests of quantum mechanics on the single atom and single photon scale which were hardly eve...
Long-distance quantum communication. Decoherence-avoiding mechanisms
Energy Technology Data Exchange (ETDEWEB)
Kolb Bernardes, Nadja
2012-12-17
Entanglement is the essence of most quantum information processes. For instance, it is used as a resource for quantum teleportation or perfectly secure classical communication. Unfortunately, inevitable noise in the quantum channel will typically affect the distribution of entanglement. Owing to fundamental principles, common procedures used in classical communication, such as amplification, cannot be applied. Therefore, the fidelity and rate of transmission will be limited by the length of the channel. Quantum repeaters were proposed to avoid the exponential decay with the distance and to permit long-distance quantum communication. Long-distance quantum communication constitutes the framework for the results presented in this thesis. The main question addressed in this thesis is how the performance of quantum repeaters are affected by various sources of decoherence. Moreover, what can be done against decoherence to improve the performance of the repeater. We are especially interested in the so-called hybrid quantum repeater; however, many of the results presented here are sufficiently general and may be applied to other systems as well. First, we present a detailed entanglement generation rate analysis for the quantum repeater. In contrast to what is commonly found in the literature, our analysis is general and analytical. Moreover, various sources of errors are considered, such as imperfect local two-qubit operations and imperfect memories, making it possible to determine the requirements for memory decoherence times. More specifically, we apply our formulae in the context of a hybrid quantum repeater and we show that in a possible experimental scenario, our hybrid system can create near-maximally entangled pairs over a distance of 1280 km at rates of the order of 100 Hz. Furthermore, aiming to protect the system against different types of errors, we analyze the hybrid quantum repeater when supplemented by quantum error correction. We propose a scheme for
Capacity of quantum Gaussian channels
Holevo, A. S.; Sohma, M.; Hirota, O.
1999-03-01
The aim of this paper is to give explicit calculation of the classical capacity of quantum Gaussian channels, in particular, involving squeezed states. The calculation is based on a general formula for the entropy of a quantum Gaussian state, which is of independent interest, and on the recently proved coding theorem for quantum communication channels.
Quantum random oracle model for quantum digital signature
Shang, Tao; Lei, Qi; Liu, Jianwei
2016-10-01
The goal of this work is to provide a general security analysis tool, namely, the quantum random oracle (QRO), for facilitating the security analysis of quantum cryptographic protocols, especially protocols based on quantum one-way function. QRO is used to model quantum one-way function and different queries to QRO are used to model quantum attacks. A typical application of quantum one-way function is the quantum digital signature, whose progress has been hampered by the slow pace of the experimental realization. Alternatively, we use the QRO model to analyze the provable security of a quantum digital signature scheme and elaborate the analysis procedure. The QRO model differs from the prior quantum-accessible random oracle in that it can output quantum states as public keys and give responses to different queries. This tool can be a test bed for the cryptanalysis of more quantum cryptographic protocols based on the quantum one-way function.
Layered Architecture for Quantum Computing
Directory of Open Access Journals (Sweden)
N. Cody Jones
2012-07-01
Full Text Available We develop a layered quantum-computer architecture, which is a systematic framework for tackling the individual challenges of developing a quantum computer while constructing a cohesive device design. We discuss many of the prominent techniques for implementing circuit-model quantum computing and introduce several new methods, with an emphasis on employing surface-code quantum error correction. In doing so, we propose a new quantum-computer architecture based on optical control of quantum dots. The time scales of physical-hardware operations and logical, error-corrected quantum gates differ by several orders of magnitude. By dividing functionality into layers, we can design and analyze subsystems independently, demonstrating the value of our layered architectural approach. Using this concrete hardware platform, we provide resource analysis for executing fault-tolerant quantum algorithms for integer factoring and quantum simulation, finding that the quantum-dot architecture we study could solve such problems on the time scale of days.
Codes in W*-Metric Spaces: Theory and Examples
Bumgardner, Christopher J.
2011-01-01
We introduce a "W*"-metric space, which is a particular approach to non-commutative metric spaces where a "quantum metric" is defined on a von Neumann algebra. We generalize the notion of a quantum code and quantum error correction to the setting of finite dimensional "W*"-metric spaces, which includes codes and error correction for classical…
Quantum engineering of continuous variable quantum states
Energy Technology Data Exchange (ETDEWEB)
Sabuncu, Metin
2009-10-29
Quantum information with continuous variables is a field attracting increasing attention recently. In continuous variable quantum information one makes use of the continuous information encoded into the quadrature of a quantized light field instead of binary quantities such as the polarization state of a single photon. This brand new research area is witnessing exciting theoretical and experimental achievements such as teleportation, quantum computation and quantum error correction. The rapid development of the field is mainly due higher optical data rates and the availability of simple and efficient manipulation tools in continuous-variable quantum information processing. We in this thesis extend the work in continuous variable quantum information processing and report on novel experiments on amplification, cloning, minimal disturbance and noise erasure protocols. The promising results we obtain in these pioneering experiments indicate that the future of continuous variable quantum information is bright and many advances can be foreseen. (orig.)
Klimov, A. N.; Kulik, S. P.; Molotkov, S. N.; Potapova, T. A.
2017-03-01
In the paper by Gleim et al (2016 Opt. Express 24 2619), it was declared that the system of quantum cryptography, exploiting quantum key distribution (QKD) protocol BB84 with the additional reference state and encoding in a sub-carrier, is able to distribute secret keys at a distance of 210 km. The following shows that a simple attack realized with a beam splitter results in a loss of privacy of the keys over substantially smaller distances. It turns out that the actual length of the secret key transmission for the QKD system encoding in the sub-carrier frequency is ten times less than that declared in Gleim et al (2016 Opt. Express 24 2619). Therefore it is impossible to safely use the keys when distributed at a larger length of the communication channel than shown below. The maximum communication distance does not exceed 22 km, even in the most optimistic scenario.
Directory of Open Access Journals (Sweden)
M Moeinifar
2017-02-01
Full Text Available One important factor in using an High Purity Germanium (HPGe detector is its efficiency that highly depends on the geometry and absorption factors, so that when the configuration of source-detector geometry is changed, the detector efficiency must be re-measured. The best way of determining the efficiency of a detector is measuring the efficiency of standard sources. But considering the fact that standard sources are hardly available and it is time consuming to find them, determinig the efficiency by simulation which gives enough efficiency in less time, is important. In this study, the dead layer thickness and the full-energy peak efficiency of an HPGe detector was obtained by Monte Carlo simulation, using MCNPX code. For this, we first measured gamma–ray spectra for different sources placed at various distances from the detector and stored the measured spectra obtained. Then the obtained spectra were simulated under similar conditions in vitro.At first, the whole volume of germanium was regarded as active, and the obtaind spectra from calculation were compared with the corresponding experimental spectra. Comparison of the calculated spectra with the measured spectra showed considerable differences. By making small variations in the dead layer thickness of the detector (about a few hundredths of a millimeter in the simulation program, we tried to remove these differences and in this way a dead layer of 0.57 mm was obtained for the detector. By incorporating this value for the dead layer in the simulating program, the full-energy peak efficiency of the detector was then obtained both by experiment and by simulation, for various sources at various distances from the detector, and both methods showed good agreements. Then, using MCNP code and considering the exact measurement system, one can conclude that the efficiency of an HPGe detector for various source-detector geometries can be calculated with rather good accuracy by simulation method
Straupe, S. S.
2016-10-01
We provide a review of the experimental and theoretical research in the field of quantum tomography with an emphasis on recently developed adaptive protocols. Several statistical frameworks for adaptive experimental design are discussed. We argue in favor of the Bayesian approach, highlighting both its advantages for a statistical reconstruction of unknown quantum states and processes, and utility for adaptive experimental design. The discussion is supported by an analysis of several recent experimental implementations and numerical recipes.
Preparation of quantum state (review)
Ali, N.; Yusof, N. R.; Soekardjo, S.; Saharudin, S.; Endut, R.
2017-11-01
We reviewed experimental results and publications prepared by the Quantum Laboratory, Mimos Berhad. The complexity of the setups lies mainly in preparing the quantum states. Optics is chosen as the medium of this quantum system. The two methods - fiber based and free space systems are different from each other in terms of experimental setups, components configuration, and selections.
Directory of Open Access Journals (Sweden)
Masego Dibetsoe
2015-08-01
Full Text Available The effects of seven macrocyclic compounds comprising four phthalocyanines (Pcs namely 1,4,8,11,15,18,22,25-octabutoxy-29H,31H-phthalocyanine (Pc1, 2,3,9,10,16,17,23,24-octakis(octyloxy-29H,31H-phthalocyanine (Pc2, 2,9,16,23-tetra-tert-butyl-29H,31H-phthalocyanine (Pc3 and 29H,31H-phthalocyanine (Pc4, and three naphthalocyanines namely 5,9,14,18,23,27,32,36-octabutoxy-2,3-naphthalocyanine (nPc1, 2,11,20,29-tetra-tert-butyl-2,3-naphthalocyanine (nPc2 and 2,3-naphthalocyanine (nP3 were investigated on the corrosion of aluminium (Al in 1 M HCl using a gravimetric method, potentiodynamic polarization technique, quantum chemical calculations and quantitative structure activity relationship (QSAR. Synergistic effects of KI on the corrosion inhibition properties of the compounds were also investigated. All the studied compounds showed appreciable inhibition efficiencies, which decrease with increasing temperature from 30 °C to 70 °C. At each concentration of the inhibitor, addition of 0.1% KI increased the inhibition efficiency compared to the absence of KI indicating the occurrence of synergistic interactions between the studied molecules and I− ions. From the potentiodynamic polarization studies, the studied Pcs and nPcs are mixed type corrosion inhibitors both without and with addition of KI. The adsorption of the studied molecules on Al surface obeys the Langmuir adsorption isotherm, while the thermodynamic and kinetic parameters revealed that the adsorption of the studied compounds on Al surface is spontaneous and involves competitive physisorption and chemisorption mechanisms. The experimental results revealed the aggregated interactions between the inhibitor molecules and the results further indicated that the peripheral groups on the compounds affect these interactions. The calculated quantum chemical parameters and the QSAR results revealed the possibility of strong interactions between the studied inhibitors and metal surface. QSAR
Orieux, Adeline; Boutari, Joelle; Barbieri, Marco; Paternostro, Mauro; Mataloni, Paolo
2014-11-24
Critical phenomena involve structural changes in the correlations of its constituents. Such changes can be reproduced and characterized in quantum simulators able to tackle medium-to-large-size systems. We demonstrate these concepts by engineering the ground state of a three-spin Ising ring by using a pair of entangled photons. The effect of a simulated magnetic field, leading to a critical modification of the correlations within the ring, is analysed by studying two- and three-spin entanglement. In particular, we connect the violation of a multipartite Bell inequality with the amount of tripartite entanglement in our ring.
Directory of Open Access Journals (Sweden)
Rolando, A.
2006-09-01
Full Text Available In this paper the compression strength of a clay brickwork masonry bound with cement mortar is analyzed. The target is to obtain the characteristic compression strength of unreinforced brickwork masonry. This research try to test the validity of the analytical equations in European codes, comparing the experimental strength with the analytically obtained from the strength of its components (clay brick and cement mortar.En este artículo se analiza la resistencia a compresión de una fábrica de ladrillo cerámico, asentado con mortero de cemento.El objetivo es obtener la resistencia característica a compresión de la fábrica sin armar.La investigación comprueba la fiabilidad de las expresiones analíticas existentes en la normativa europea, comparando la resistencia obtenida experimentalmente con la obtenida analíticamente, a partir de la resistencia de sus componentes (ladrillo cerámico y mortero de cemento.
Quantum steganography using prior entanglement
Energy Technology Data Exchange (ETDEWEB)
Mihara, Takashi, E-mail: mihara@toyo.jp
2015-06-05
Steganography is the hiding of secret information within innocent-looking information (e.g., text, audio, image, video, etc.). A quantum version of steganography is a method based on quantum physics. In this paper, we propose quantum steganography by combining quantum error-correcting codes with prior entanglement. In many steganographic techniques, embedding secret messages in error-correcting codes may cause damage to them if the embedded part is corrupted. However, our proposed steganography can separately create secret messages and the content of cover messages. The intrinsic form of the cover message does not have to be modified for embedding secret messages. - Highlights: • Our steganography combines quantum error-correcting codes with prior entanglement. • Our steganography can separately create secret messages and the content of cover messages. • Errors in cover messages do not have affect the recovery of secret messages. • We embed a secret message in the Steane code as an example of our steganography.
Quantum dots for quantum information technologies
2017-01-01
This book highlights the most recent developments in quantum dot spin physics and the generation of deterministic superior non-classical light states with quantum dots. In particular, it addresses single quantum dot spin manipulation, spin-photon entanglement and the generation of single-photon and entangled photon pair states with nearly ideal properties. The role of semiconductor microcavities, nanophotonic interfaces as well as quantum photonic integrated circuits is emphasized. The latest theoretical and experimental studies of phonon-dressed light matter interaction, single-dot lasing and resonance fluorescence in QD cavity systems are also provided. The book is written by the leading experts in the field.
Gutiérrez, Ricardo; Simonelli, Cristiano; Archimi, Matteo; Castellucci, Francesco; Arimondo, Ennio; Ciampini, Donatella; Marcuzzi, Matteo; Lesanovsky, Igor; Morsch, Oliver
2017-10-01
Understanding and probing phase transitions in nonequilibrium systems is an ongoing challenge in physics. A particular instance are phase transitions that occur between a nonfluctuating absorbing phase, e.g., an extinct population, and one in which the relevant order parameter, such as the population density, assumes a finite value. Here, we report the observation of signatures of such a nonequilibrium phase transition in an open driven quantum system. In our experiment, rubidium atoms in a quasi-one-dimensional cold disordered gas are laser excited to Rydberg states under so-called facilitation conditions. This conditional excitation process competes with spontaneous decay and leads to a crossover between a stationary state with no excitations and one with a finite number of excitations. We relate the underlying physics to that of an absorbing-state phase transition in the presence of a field (i.e., off-resonant excitation processes) which slightly offsets the system from criticality. We observe a characteristic power-law scaling of the Rydberg excitation density as well as increased fluctuations close to the transition point. Furthermore, we argue that the observed transition relies on the presence of atomic motion which introduces annealed disorder into the system and enables the formation of long-ranged correlations. Our study paves the road for future investigations into the largely unexplored physics of nonequilibrium phase transitions in open many-body quantum systems.
Quantum Erasure: Quantum Interference Revisited
Walborn, Stephen P.; Cunha, Marcelo O. Terra; Pádua, Sebastião; Monken, Carlos H.
2005-01-01
Recent experiments in quantum optics have shed light on the foundations of quantum physics. Quantum erasers - modified quantum interference experiments - show that quantum entanglement is responsible for the complementarity principle.
Wilde, Mark M
2017-01-01
Developing many of the major, exciting, pre- and post-millennium developments from the ground up, this book is an ideal entry point for graduate students into quantum information theory. Significant attention is given to quantum mechanics for quantum information theory, and careful studies of the important protocols of teleportation, superdense coding, and entanglement distribution are presented. In this new edition, readers can expect to find over 100 pages of new material, including detailed discussions of Bell's theorem, the CHSH game, Tsirelson's theorem, the axiomatic approach to quantum channels, the definition of the diamond norm and its interpretation, and a proof of the Choi–Kraus theorem. Discussion of the importance of the quantum dynamic capacity formula has been completely revised, and many new exercises and references have been added. This new edition will be welcomed by the upcoming generation of quantum information theorists and the already established community of classical information theo...
Directory of Open Access Journals (Sweden)
Elezov M.S.
2017-01-01
Full Text Available Recently bright-light control of the SSPD has been demonstrated. This attack employed a “backdoor” in the detector biasing scheme. Under bright-light illumination, SSPD becomes resistive and remains “latched” in the resistive state even when the light is switched off. While the SSPD is latched, Eve can simulate SSPD single-photon response by sending strong light pulses, thus deceiving Bob. We developed the experimental setup for investigation of a dependence on latching threshold of SSPD on optical pulse length and peak power. By knowing latching threshold it is possible to understand essential requirements for development countermeasures against blinding attack on quantum key distribution system with SSPDs.
Shi, Chao; Li, Zhili; Ren, Wei
2016-11-01
This article presents the experimental and modeling study of quartz-enhanced photoacoustic detection of nitrogen monoxide (NO) using the off-beam configuration and a distributed-feedback (DFB) quantum cascade laser (QCL) at 5.26 μm as the excitation source. Trace gas monitoring of NO is one of the important subjects for both environmental protection and human health monitoring. Quartz-enhanced photoacoustic spectroscopy (QEPAS) with on-beam configuration is mostly adopted for gas detection. In comparison, the off-beam approach has not only comparative detection sensitivity but also significant advantage of simpler installation and optical alignment. We optimized the sensor performance by adjusting the horizontal and vertical distances between the micro-resonator (mR) and the QTF prongs. Pressure and humidity are two important factors affecting the photoacoustic signal. The effects of both parameters on the NO concentration determination were investigated.
Straupe, Stanislav
2016-01-01
We provide a review of the experimental and theoretical research in the field of quantum tomography with an emphasis on recently developed adaptive protocols. Several statistical frameworks for adaptive experimental design are discussed. We argue in favor of the Bayesian approach, highlighting both its advantages for a statistical reconstruction of unknown quantum states and processes, and utility for adaptive experimental design. The discussion is supported by an analysis of several recent e...
Energy Technology Data Exchange (ETDEWEB)
Ullah, Sami; Bustam, Mohamad Azmi; Shariff, Azmi Mohamad; Gonfa, Girma, E-mail: kiyaagonfaa@gmail.com; Izzat, Khairul
2016-03-01
Graphical abstract: - Highlights: • Corrosion behavior of [C{sub 4}C{sub 1}im][FeCl{sub 4}] towards A36 mild steel were studied. • Corrosion of [C{sub 4}C{sub 1}im][FeCl{sub 4}] towards steel is higher in open environment. • Higher water content and temperature results in higher corrosions. • Quantum chemical calculations were performed to understand the ionic liquid–mild steel interactions. - Abstract: The corrosion behaviour of ionic liquid 1-butyl-3-methylimidazolium tetrachloroferrate ([C{sub 4}C{sub 1}im][FeCl{sub 4}]) towards A36 mild steel was studied through experiments and quantum calculations. The corrosion rates were obtained through immersion tests both in open and controlled environments. The surface morphology of the A36 mild steel was investigated using scanning electron microscopy (SEM). The effects of temperature and water content on the corrosion of the ionic liquid towards A36 mild steel were studied through electrochemical corrosion measurement techniques. The results show that the corrosion of [C{sub 4}C{sub 1}im][FeCl{sub 4}] towards the mild steel in the open environment is 17 times higher than in the control environment. The corrosion rate increases with increasing temperature and water content in [C{sub 4}C{sub 1}im][FeCl{sub 4}]. Density Functional Theory (DFT) calculations were performed to gain some insight into the interactions of [C{sub 4}C{sub 1}im][FeCl{sub 4}] with the A36 mild steels surface.
1983-01-01
The verified code for the SIFT Executive is not the code that executes on the SIFT system as delivered. The running versions of the SIFT Executive contain optimizations and special code relating to the messy interface to the hardware broadcast interface and to packing of data to conserve space in the store of the BDX930 processors. The running code was in fact developed prior to and without consideration of any mechanical verification. This was regarded as necessary experimentation with the SIFT hardware and special purpose Pascal compiler. The Pascal code sections cover: the selection of a schedule from the global executive broadcast, scheduling, dispatching, three way voting, and error reporting actions of the SIFT Executive. Not included in these sections of Pascal code are: the global executive, five way voting, clock synchronization, interactive consistency, low level broadcasting, and program loading, initialization, and schedule construction.
Energy Technology Data Exchange (ETDEWEB)
Lopes, E.M., E-mail: eldermantovani@yahoo.com.br [Departamento de Física, Química e Biologia, Universidade Estadual Paulista, C. P. 266, Presidente Prudente, São Paulo 17700-000 (Brazil); César, D.F. [Departamento de Física, Universidade Federal de São Carlos, C. P. 676, São Carlos, São Paulo (Brazil); Franchello, F.; Duarte, J.L.; Dias, I.F.L.; Laureto, E. [Departamento de Física, Universidade Estadual de Londrina, C. P. 6001, Londrina, Paraná (Brazil); Elias, D.C.; Pereira, M.V.M.; Guimarães, P.S.S. [Departamento de Física, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, C. P. 702, Belo Horizonte, Minas Gerais (Brazil); Quivy, A.A. [Laboratório de Novos Materiais Semicondutores, Instituto de Física, Universidade de São Paulo, C. P. 66318, São Paulo (Brazil)
2013-12-15
This paper discusses the theoretical and experimental results obtained for the excitonic binding energy (E{sub b}) in a set of single and coupled double quantum wells (SQWs and CDQWs) of GaAs/AlGaAs with different Al concentrations (Al%) and inter-well barrier thicknesses. To obtain the theoretical E{sub b} the method proposed by Mathieu, Lefebvre and Christol (MLC) was used, which is based on the idea of fractional-dimension space, together with the approach proposed by Zhao et al., which extends the MLC method for application in CDQWs. Through magnetophotoluminescence (MPL) measurements performed at 4 K with magnetic fields ranging from 0 T to 12 T, the diamagnetic shift curves were plotted and adjusted using two expressions: one appropriate to fit the curve in the range of low intensity fields and another for the range of high intensity fields, providing the experimental E{sub b} values. The effects of increasing the Al% and the inter-well barrier thickness on E{sub b} are discussed. The E{sub b} reduction when going from the SQW to the CDQW with 5 Å inter-well barrier is clearly observed experimentally for 35% Al concentration and this trend can be noticed even for concentrations as low as 25% and 15%, although the E{sub b} variations in these latter cases are within the error bars. As the Zhao's approach is unable to describe this effect, the wave functions and the probability densities for electrons and holes were calculated, allowing us to explain this effect as being due to a decrease in the spatial superposition of the wave functions caused by the thin inter-well barrier. -- Highlights: • Magnetophotoluminescence results from coupled double quantum wells are reported. • Theoretical and experimental values for excitonic binding energy (E{sub b}) are obtained. • The effects of increasing the inter-well barrier height and thickness on E{sub b} are discussed. • An E{sub b} reduction is observed when going from zero to the 5 Å inter-well barrier
Schindelhauer, Christian; Jakoby, Andreas; Köhler, Sven
2016-01-01
We introduce Cyclone codes which are rateless erasure resilient codes. They combine Pair codes with Luby Transform (LT) codes by computing a code symbol from a random set of data symbols using bitwise XOR and cyclic shift operations. The number of data symbols is chosen according to the Robust Soliton distribution. XOR and cyclic shift operations establish a unitary commutative ring if data symbols have a length of $p-1$ bits, for some prime number $p$. We consider the graph given by code sym...
Quantum optics with semiconductor nanostructures
Jahnke, Frank
2012-01-01
A guide to the theory, application and potential of semiconductor nanostructures in the exploration of quantum optics. It offers an overview of resonance fluorescence emission.$bAn understanding of the interaction between light and matter on a quantum level is of fundamental interest and has many applications in optical technologies. The quantum nature of the interaction has recently attracted great attention for applications of semiconductor nanostructures in quantum information processing. Quantum optics with semiconductor nanostructures is a key guide to the theory, experimental realisation, and future potential of semiconductor nanostructures in the exploration of quantum optics. Part one provides a comprehensive overview of single quantum dot systems, beginning with a look at resonance fluorescence emission. Quantum optics with single quantum dots in photonic crystal and micro cavities are explored in detail, before part two goes on to review nanolasers with quantum dot emitters. Light-matter interaction...
Directory of Open Access Journals (Sweden)
Fabio Burderi
2007-05-01
Full Text Available Motivated by the study of decipherability conditions for codes weaker than Unique Decipherability (UD, we introduce the notion of coding partition. Such a notion generalizes that of UD code and, for codes that are not UD, allows to recover the ``unique decipherability" at the level of the classes of the partition. By tacking into account the natural order between the partitions, we define the characteristic partition of a code X as the finest coding partition of X. This leads to introduce the canonical decomposition of a code in at most one unambiguouscomponent and other (if any totally ambiguouscomponents. In the case the code is finite, we give an algorithm for computing its canonical partition. This, in particular, allows to decide whether a given partition of a finite code X is a coding partition. This last problem is then approached in the case the code is a rational set. We prove its decidability under the hypothesis that the partition contains a finite number of classes and each class is a rational set. Moreover we conjecture that the canonical partition satisfies such a hypothesis. Finally we consider also some relationships between coding partitions and varieties of codes.
Quantum memories: emerging applications and recent advances.
Heshami, Khabat; England, Duncan G; Humphreys, Peter C; Bustard, Philip J; Acosta, Victor M; Nunn, Joshua; Sussman, Benjamin J
2016-11-12
Quantum light-matter interfaces are at the heart of photonic quantum technologies. Quantum memories for photons, where non-classical states of photons are mapped onto stationary matter states and preserved for subsequent retrieval, are technical realizations enabled by exquisite control over interactions between light and matter. The ability of quantum memories to synchronize probabilistic events makes them a key component in quantum repeaters and quantum computation based on linear optics. This critical feature has motivated many groups to dedicate theoretical and experimental research to develop quantum memory devices. In recent years, exciting new applications, and more advanced developments of quantum memories, have proliferated. In this review, we outline some of the emerging applications of quantum memories in optical signal processing, quantum computation and non-linear optics. We review recent experimental and theoretical developments, and their impacts on more advanced photonic quantum technologies based on quantum memories.
1990-01-01
Quantum electrodynamics is an essential building block and an integral part of the gauge theory of unified electromagnetic, weak, and strong interactions, the so-called standard model. Its failure or breakdown at some level would have a most profound impact on the theoretical foundations of elementary particle physics as a whole. Thus the validity of QED has been the subject of intense experimental tests over more than 40 years of its history. This volume presents an up-to-date review of high precision experimental tests of QED together with comprehensive discussion of required theoretical wor
DEFF Research Database (Denmark)
Ejsing-Duun, Stine; Hansbøl, Mikala
Sammenfatning af de mest væsentlige pointer fra hovedrapporten: Dokumentation og evaluering af Coding Class......Sammenfatning af de mest væsentlige pointer fra hovedrapporten: Dokumentation og evaluering af Coding Class...
Gutierrez, Ricardo; Archimi, Matteo; Castellucci, Francesco; Arimondo, Ennio; Ciampini, Donatella; Marcuzzi, Matteo; Lesanovsky, Igor; Morsch, Oliver
2016-01-01
Understanding and probing phase transitions in non-equilibrium systems is an ongoing challenge in physics. A particular instance are phase transitions that occur between a non-fluctuating absorbing phase, e.g., an extinct population, and one in which the relevant order parameter, such as the population density, assumes a finite value. Here we report the observation of signatures of such a non-equilibrium phase transition in an open driven quantum system. In our experiment rubidium atoms in a quasi one-dimensional cold disordered gas are laser-excited to Rydberg states under so-called facilitation conditions. This conditional excitation process competes with spontaneous decay and leads to a crossover between a stationary state with no excitations and one with a finite number of excitations. We relate the underlying physics to that of an absorbing state phase transition in the presence of a field which slightly offsets the system from criticality. We observe a characteristic power-law scaling of the Rydberg exc...
Directory of Open Access Journals (Sweden)
Ishac Bertran
2012-08-01
Full Text Available "Exploring the potential of code to communicate at the level of poetry," the code {poems} project solicited submissions from codewriters in response to the notion of a poem, written in a software language which is semantically valid. These selections reveal the inner workings, constitutive elements, and styles of both a particular software and its authors.
Quantum simulation of a quantum stochastic walk
Govia, Luke C. G.; Taketani, Bruno G.; Schuhmacher, Peter K.; Wilhelm, Frank K.
2017-03-01
The study of quantum walks has been shown to have a wide range of applications in areas such as artificial intelligence, the study of biological processes, and quantum transport. The quantum stochastic walk (QSW), which allows for incoherent movement of the walker, and therefore, directionality, is a generalization on the fully coherent quantum walk. While a QSW can always be described in Lindblad formalism, this does not mean that it can be microscopically derived in the standard weak-coupling limit under the Born-Markov approximation. This restricts the class of QSWs that can be experimentally realized in a simple manner. To circumvent this restriction, we introduce a technique to simulate open system evolution on a fully coherent quantum computer, using a quantum trajectories style approach. We apply this technique to a broad class of QSWs, and show that they can be simulated with minimal experimental resources. Our work opens the path towards the experimental realization of QSWs on large graphs with existing quantum technologies.
Li, Shu-shen; Long, Gui-Lu; Bai, Feng-Shan; Feng, Song-Lin; Zheng, Hou-Zhi
2001-01-01
Quantum computing is a quickly growing research field. This article introduces the basic concepts of quantum computing, recent developments in quantum searching, and decoherence in a possible quantum dot realization.
Topics in quantum cryptography, quantum error correction, and channel simulation
Luo, Zhicheng
In this thesis, we mainly investigate four different topics: efficiently implementable codes for quantum key expansion [51], quantum error-correcting codes based on privacy amplification [48], private classical capacity of quantum channels [44], and classical channel simulation with quantum side information [49, 50]. For the first topic, we propose an efficiently implementable quantum key expansion protocol, capable of increasing the size of a pre-shared secret key by a constant factor. Previously, the Shor-Preskill proof [64] of the security of the Bennett-Brassard 1984 (BB84) [6] quantum key distribution protocol relied on the theoretical existence of good classical error-correcting codes with the "dual-containing" property. But the explicit and efficiently decodable construction of such codes is unknown. We show that we can lift the dual-containing constraint by employing the non-dual-containing codes with excellent performance and efficient decoding algorithms. For the second topic, we propose a construction of Calderbank-Shor-Steane (CSS) [19, 68] quantum error-correcting codes, which are originally based on pairs of mutually dual-containing classical codes, by combining a classical code with a two-universal hash function. We show, using the results of Renner and Koenig [57], that the communication rates of such codes approach the hashing bound on tensor powers of Pauli channels in the limit of large block-length. For the third topic, we prove a regularized formula for the secret key assisted capacity region of a quantum channel for transmitting private classical information. This result parallels the work of Devetak on entanglement assisted quantum communication capacity. This formula provides a new family protocol, the private father protocol, under the resource inequality framework that includes the private classical communication without the assisted secret keys as a child protocol. For the fourth topic, we study and solve the problem of classical channel
Detecting Quantum Entanglement
Terhal, Barbara M
2001-01-01
We review the criteria for separability and quantum entanglement, both in a bipartite as well as a multipartite setting. We discuss Bell inequalities, entanglement witnesses, entropic inequalities, bound entanglement and several features of multipartite entanglement. We indicate how these criteria bear on the experimental detection of quantum entanglement.
Quantifying quantum coherence with quantum Fisher information.
Feng, X N; Wei, L F
2017-11-14
Quantum coherence is one of the old but always important concepts in quantum mechanics, and now it has been regarded as a necessary resource for quantum information processing and quantum metrology. However, the question of how to quantify the quantum coherence has just been paid the attention recently (see, e.g., Baumgratz et al. PRL, 113. 140401 (2014)). In this paper we verify that the well-known quantum Fisher information (QFI) can be utilized to quantify the quantum coherence, as it satisfies the monotonicity under the typical incoherent operations and the convexity under the mixing of the quantum states. Differing from most of the pure axiomatic methods, quantifying quantum coherence by QFI could be experimentally testable, as the bound of the QFI is practically measurable. The validity of our proposal is specifically demonstrated with the typical phase-damping and depolarizing evolution processes of a generic single-qubit state, and also by comparing it with the other quantifying methods proposed previously.
Coding vs non-coding: Translatability of short ORFs found in putative non-coding transcripts.
Kageyama, Yuji; Kondo, Takefumi; Hashimoto, Yoshiko
2011-11-01
Genome analysis has identified a number of putative non-protein-coding transcripts that do not contain ORFs longer than 100 codons. Although evidence strongly suggests that non-coding RNAs are important in a variety of biological phenomena, the discovery of small peptide-coding mRNAs confirms that some transcripts that have been assumed to be non-coding actually have coding potential. Their abundance and importance in biological phenomena makes the sorting of non-coding RNAs from small peptide-coding mRNAs a key issue in functional genomics. However, validating the coding potential of small peptide-coding RNAs is complicated, because their ORF sequences are usually too short for computational analysis. In this review, we discuss computational and experimental methods for validating the translatability of these non-coding RNAs. Copyright © 2011 Elsevier Masson SAS. All rights reserved.
Quantum Simulation and Quantum Sensing with Ultracold Strontium
2015-09-18
AFRL-AFOSR-VA-TR-2015-0346 Quantum Simulation and Quantum Sensing with Ultracold Strontium David Weld UNIVERSITY OF CALIFORNIA SANTA BARBARA Final...June 2012 - June 2015 Quantum Simulation and Quantum Sensing with Ultracold Strontium FA9550-12-1-0305 Weld, David M. University of California, Santa...Arlington VA 22203 Approved for public release. We have built an ultra-high vacuum experimental apparatus for trapping and cooling of strontium , demonstrated
Understanding quantum phase transitions
Carr, Lincoln
2010-01-01
Quantum phase transitions (QPTs) offer wonderful examples of the radical macroscopic effects inherent in quantum physics: phase changes between different forms of matter driven by quantum rather than thermal fluctuations, typically at very low temperatures. QPTs provide new insight into outstanding problems such as high-temperature superconductivity and display fundamental aspects of quantum theory, such as strong correlations and entanglement. Over the last two decades, our understanding of QPTs has increased tremendously due to a plethora of experimental examples, powerful new numerical meth
On quantum statistical inference
DEFF Research Database (Denmark)
Barndorff-Nielsen, Ole Eiler; Gill, Richard D.; Jupp, Peter E.
Recent developments in the mathematical foundations of quantum mechanics have brought the theory closer to that of classical probability and statistics. On the other hand, the unique character of quantum physics sets many of the questions addressed apart from those met classically in stochastics....... Furthermore, concurrent advances in experimental techniques and in the theory of quantum computation have led to a strong interest in questions of quantum information, in particular in the sense of the amount of information about unknown parameters in given observational data or accessible through various...
Quantum information and computing
Ohya, M; Watanabe, N
2006-01-01
The main purpose of this volume is to emphasize the multidisciplinary aspects of this very active new line of research in which concrete technological and industrial realizations require the combined efforts of experimental and theoretical physicists, mathematicians and engineers. Contents: Coherent Quantum Control of ?-Atoms through the Stochastic Limit (L Accardi et al.); Recent Advances in Quantum White Noise Calculus (L Accardi & A Boukas); Joint Extension of States of Fermion Subsystems (H Araki); Fidelity of Quantum Teleportation Model Using Beam Splittings (K-H Fichtner et al.); Quantum
Relativistic quantum chemistry on quantum computers
DEFF Research Database (Denmark)
Veis, L.; Visnak, J.; Fleig, T.
2012-01-01
The past few years have witnessed a remarkable interest in the application of quantum computing for solving problems in quantum chemistry more efficiently than classical computers allow. Very recently, proof-of-principle experimental realizations have been reported. However, so far only...... the nonrelativistic regime (i.e., the Schrodinger equation) has been explored, while it is well known that relativistic effects can be very important in chemistry. We present a quantum algorithm for relativistic computations of molecular energies. We show how to efficiently solve the eigenproblem of the Dirac......-Coulomb Hamiltonian on a quantum computer and demonstrate the functionality of the proposed procedure by numerical simulations of computations of the spin-orbit splitting in the SbH molecule. Finally, we propose quantum circuits with three qubits and nine or ten controlled-NOT (CNOT) gates, which implement a proof...
Toric Codes, Multiplicative Structure and Decoding
DEFF Research Database (Denmark)
Hansen, Johan Peder
2017-01-01
and aligns with decoding by error correcting pairs. We have used the multiplicative structure on toric codes to construct linear secret sharing schemes with \\emph{strong multiplication} via Massey's construction generalizing the Shamir Linear secret sharing shemes constructed from Reed-Solomon codes. We have...... constructed quantum error correcting codes from toric surfaces by the Calderbank-Shor-Steane method.......Long linear codes constructed from toric varieties over finite fields, their multiplicative structure and decoding. The main theme is the inherent multiplicative structure on toric codes. The multiplicative structure allows for \\emph{decoding}, resembling the decoding of Reed-Solomon codes...
Quantum information and convex optimization
Energy Technology Data Exchange (ETDEWEB)
Reimpell, Michael
2008-07-01
This thesis is concerned with convex optimization problems in quantum information theory. It features an iterative algorithm for optimal quantum error correcting codes, a postprocessing method for incomplete tomography data, a method to estimate the amount of entanglement in witness experiments, and it gives necessary and sufficient criteria for the existence of retrodiction strategies for a generalized mean king problem. (orig.)
Baaquie, Belal E; Demongeot, J; Galli-Carminati, Giuliana; Martin, F; Teodorani, Massimo
2015-01-01
At the end of the 19th century Sigmund Freud discovered that our acts and choices are not only decisions of our consciousness, but that they are also deeply determined by our unconscious (the so-called "Freudian unconscious"). During a long correspondence between them (1932-1958) Wolfgang Pauli and Carl Gustav Jung speculated that the unconscious could be a quantum system. This book is addressed both to all those interested in the new developments of the age-old enquiry in the relations between mind and matter, and also to the experts in quantum physics that are interested in a formalisation of this new approach. The description of the "Bilbao experiment" adds a very interesting experimental inquiry into the synchronicity effect in a group situation, linking theory to a quantifiable verification of these subtle effects. Cover design: "Entangled Minds". Riccardo Carminati Galli, 2014.
Quantum Distinction: Quantum Distinctiones!
Zeps, Dainis
2009-01-01
10 pages; How many distinctions, in Latin, quantum distinctiones. We suggest approach of anthropic principle based on anthropic reference system which should be applied equally both in theoretical physics and in mathematics. We come to principle that within reference system of life subject of mathematics (that of thinking) should be equated with subject of physics (that of nature). For this reason we enter notions of series of distinctions, quantum distinction, and argue that quantum distinct...
Code Properties from Holographic Geometries
Directory of Open Access Journals (Sweden)
Fernando Pastawski
2017-05-01
Full Text Available Almheiri, Dong, and Harlow [J. High Energy Phys. 04 (2015 163.JHEPFG1029-847910.1007/JHEP04(2015163] proposed a highly illuminating connection between the AdS/CFT holographic correspondence and operator algebra quantum error correction (OAQEC. Here, we explore this connection further. We derive some general results about OAQEC, as well as results that apply specifically to quantum codes that admit a holographic interpretation. We introduce a new quantity called price, which characterizes the support of a protected logical system, and find constraints on the price and the distance for logical subalgebras of quantum codes. We show that holographic codes defined on bulk manifolds with asymptotically negative curvature exhibit uberholography, meaning that a bulk logical algebra can be supported on a boundary region with a fractal structure. We argue that, for holographic codes defined on bulk manifolds with asymptotically flat or positive curvature, the boundary physics must be highly nonlocal, an observation with potential implications for black holes and for quantum gravity in AdS space at distance scales that are small compared to the AdS curvature radius.
Code Properties from Holographic Geometries
Pastawski, Fernando; Preskill, John
2017-04-01
Almheiri, Dong, and Harlow [J. High Energy Phys. 04 (2015) 163., 10.1007/JHEP04(2015)163] proposed a highly illuminating connection between the AdS /CFT holographic correspondence and operator algebra quantum error correction (OAQEC). Here, we explore this connection further. We derive some general results about OAQEC, as well as results that apply specifically to quantum codes that admit a holographic interpretation. We introduce a new quantity called price, which characterizes the support of a protected logical system, and find constraints on the price and the distance for logical subalgebras of quantum codes. We show that holographic codes defined on bulk manifolds with asymptotically negative curvature exhibit uberholography, meaning that a bulk logical algebra can be supported on a boundary region with a fractal structure. We argue that, for holographic codes defined on bulk manifolds with asymptotically flat or positive curvature, the boundary physics must be highly nonlocal, an observation with potential implications for black holes and for quantum gravity in AdS space at distance scales that are small compared to the AdS curvature radius.
Energy Technology Data Exchange (ETDEWEB)
Skubic, P. [Univ. of Oklahoma, Norman, OK (United States); Abbott, B. [Univ. of Oklahoma, Norman, OK (United States); Gutierrez, P. [Univ. of Oklahoma, Norman, OK (United States); Strauss, M. [Univ. of Oklahoma, Norman, OK (United States); Kalbfleisch, G. [Univ. of Oklahoma, Norman, OK (United States); Kao, C. [Univ. of Oklahoma, Norman, OK (United States); Milton, K. A. [Univ. of Oklahoma, Norman, OK (United States)
2004-07-01
Task A: during the past three years, the D collaboration has gone from a period that has concentrated on the analysis of Run I data and the construction of the Run II detector, to the commissioning of the Run II detector and the start of Run II analysis with ≈214 pb^{₋1} data recorded so far. During the coming years, we expect to collect a factor of 30 to 60 times more data than we did during Run I. This data will be used to test the limits of the standard model (SM), search for new phenomena, and possibly see hints of the Higgs boson. Task B: A major thrust for the past eight years has been based on our experimental project to search for magnetic monopoles produced at Fermilab. Although the experiment has now been concluded, with a nal paper submitted to Physical Review D, theoretically much work remains to be done. A proper interpretation of the experimental results requires improved calculations, both relativistic and nonrelativistic, of the binding of monopoles to atomic nuclei through the anomalous magnetic moment interaction. Improved calculations of the production of monopoles through the Drell-Yan process are also being carried out.
Integrated photonic quantum walks
Gräfe, Markus; Heilmann, René; Lebugle, Maxime; Guzman-Silva, Diego; Perez-Leija, Armando; Szameit, Alexander
2016-10-01
Over the last 20 years quantum walks (QWs) have gained increasing interest in the field of quantum information science and processing. In contrast to classical walkers, quantum objects exhibit intrinsic properties like non-locality and non-classical many-particle correlations, which renders QWs a versatile tool for quantum simulation and computation as well as for a deeper understanding of genuine quantum mechanics. Since they are highly controllable and hardly interact with their environment, photons seem to be ideally suited quantum walkers. In order to study and exploit photonic QWs, lattice structures that allow low loss coherent evolution of quantum states are demanded. Such requirements are perfectly met by integrated optical waveguide devices that additionally allow a substantial miniaturization of experimental settings. Moreover, by utilizing the femtosecond direct laser writing technique three-dimensional waveguide structures are capable of analyzing QWs also on higher dimensional geometries. In this context, advances and findings of photonic QWs are discussed in this review. Various concepts and experimental results are presented covering, such as different quantum transport regimes, the Boson sampling problem, and the discrete fractional quantum Fourier transform.
Quantum sampling problems, BosonSampling and quantum supremacy
Lund, A. P.; Bremner, Michael J.; Ralph, T. C.
2017-04-01
There is a large body of evidence for the potential of greater computational power using information carriers that are quantum mechanical over those governed by the laws of classical mechanics. But the question of the exact nature of the power contributed by quantum mechanics remains only partially answered. Furthermore, there exists doubt over the practicality of achieving a large enough quantum computation that definitively demonstrates quantum supremacy. Recently the study of computational problems that produce samples from probability distributions has added to both our understanding of the power of quantum algorithms and lowered the requirements for demonstration of fast quantum algorithms. The proposed quantum sampling problems do not require a quantum computer capable of universal operations and also permit physically realistic errors in their operation. This is an encouraging step towards an experimental demonstration of quantum algorithmic supremacy. In this paper, we will review sampling problems and the arguments that have been used to deduce when sampling problems are hard for classical computers to simulate. Two classes of quantum sampling problems that demonstrate the supremacy of quantum algorithms are BosonSampling and Instantaneous Quantum Polynomial-time Sampling. We will present the details of these classes and recent experimental progress towards demonstrating quantum supremacy in BosonSampling.
Quantum chemistry simulation on quantum computers: theories and experiments.
Lu, Dawei; Xu, Boruo; Xu, Nanyang; Li, Zhaokai; Chen, Hongwei; Peng, Xinhua; Xu, Ruixue; Du, Jiangfeng
2012-07-14
It has been claimed that quantum computers can mimic quantum systems efficiently in the polynomial scale. Traditionally, those simulations are carried out numerically on classical computers, which are inevitably confronted with the exponential growth of required resources, with the increasing size of quantum systems. Quantum computers avoid this problem, and thus provide a possible solution for large quantum systems. In this paper, we first discuss the ideas of quantum simulation, the background of quantum simulators, their categories, and the development in both theories and experiments. We then present a brief introduction to quantum chemistry evaluated via classical computers followed by typical procedures of quantum simulation towards quantum chemistry. Reviewed are not only theoretical proposals but also proof-of-principle experimental implementations, via a small quantum computer, which include the evaluation of the static molecular eigenenergy and the simulation of chemical reaction dynamics. Although the experimental development is still behind the theory, we give prospects and suggestions for future experiments. We anticipate that in the near future quantum simulation will become a powerful tool for quantum chemistry over classical computations.
Quantum physics meets biology.
Arndt, Markus; Juffmann, Thomas; Vedral, Vlatko
2009-12-01
Quantum physics and biology have long been regarded as unrelated disciplines, describing nature at the inanimate microlevel on the one hand and living species on the other hand. Over the past decades the life sciences have succeeded in providing ever more and refined explanations of macroscopic phenomena that were based on an improved understanding of molecular structures and mechanisms. Simultaneously, quantum physics, originally rooted in a world-view of quantum coherences, entanglement, and other nonclassical effects, has been heading toward systems of increasing complexity. The present perspective article shall serve as a "pedestrian guide" to the growing interconnections between the two fields. We recapitulate the generic and sometimes unintuitive characteristics of quantum physics and point to a number of applications in the life sciences. We discuss our criteria for a future "quantum biology," its current status, recent experimental progress, and also the restrictions that nature imposes on bold extrapolations of quantum theory to macroscopic phenomena.
Tan, Kuan Yen; Partanen, Matti; Lake, Russell E.; Govenius, Joonas; Masuda, Shumpei; Möttönen, Mikko
2017-05-01
Quantum technology promises revolutionizing applications in information processing, communications, sensing and modelling. However, efficient on-demand cooling of the functional quantum degrees of freedom remains challenging in many solid-state implementations, such as superconducting circuits. Here we demonstrate direct cooling of a superconducting resonator mode using voltage-controllable electron tunnelling in a nanoscale refrigerator. This result is revealed by a decreased electron temperature at a resonator-coupled probe resistor, even for an elevated electron temperature at the refrigerator. Our conclusions are verified by control experiments and by a good quantitative agreement between theory and experimental observations at various operation voltages and bath temperatures. In the future, we aim to remove spurious dissipation introduced by our refrigerator and to decrease the operational temperature. Such an ideal quantum-circuit refrigerator has potential applications in the initialization of quantum electric devices. In the superconducting quantum computer, for example, fast and accurate reset of the quantum memory is needed.
Tan, Kuan Yen; Partanen, Matti; Lake, Russell E.; Govenius, Joonas; Masuda, Shumpei; Möttönen, Mikko
2017-01-01
Quantum technology promises revolutionizing applications in information processing, communications, sensing and modelling. However, efficient on-demand cooling of the functional quantum degrees of freedom remains challenging in many solid-state implementations, such as superconducting circuits. Here we demonstrate direct cooling of a superconducting resonator mode using voltage-controllable electron tunnelling in a nanoscale refrigerator. This result is revealed by a decreased electron temperature at a resonator-coupled probe resistor, even for an elevated electron temperature at the refrigerator. Our conclusions are verified by control experiments and by a good quantitative agreement between theory and experimental observations at various operation voltages and bath temperatures. In the future, we aim to remove spurious dissipation introduced by our refrigerator and to decrease the operational temperature. Such an ideal quantum-circuit refrigerator has potential applications in the initialization of quantum electric devices. In the superconducting quantum computer, for example, fast and accurate reset of the quantum memory is needed. PMID:28480900
Kong, Chang Sun; Haverty, Michael; Simka, Harsono; Shankar, Sadasivan; Rajan, Krishna
2017-09-01
We present a hybrid approach based on both machine learning and targeted ab-initio calculations to determine adhesion energies between dissimilar materials. The goals of this approach are to complement experimental and/or all ab-initio computational efforts, to identify promising materials rapidly and identify in a quantitative manner the relative contributions of the different material attributes affecting adhesion. Applications of the methodology to predict bulk modulus, yield strength, adhesion and wetting properties of copper (Cu) with other materials including metals, nitrides and oxides is discussed in this paper. In the machine learning component of this methodology, the parameters that were chosen can be roughly divided into four types: atomic and crystalline parameters (which are related to specific elements such as electronegativities, electron densities in Wigner-Seitz cells); bulk material properties (e.g. melting point), mechanical properties (e.g. modulus) and those representing atomic characteristics in ab-initio formalisms (e.g. pseudopotentials). The atomic parameters are defined over one dataset to determine property correlation with published experimental data. We then develop a semi-empirical model across multiple datasets to predict adhesion in material interfaces outside the original datasets. Since adhesion is between two materials, we appropriately use parameters which indicate differences between the elements that comprise the materials. These semi-empirical predictions agree reasonably with the trend in chemical work of adhesion predicted using ab-initio techniques and are used for fast materials screening. For the screened candidates, the ab-initio modeling component provides fundamental understanding of the chemical interactions at the interface, and explains the wetting thermodynamics of thin Cu layers on various substrates. Comparison against ultra-high vacuum (UHV) experiments for well-characterized Cu/Ta and Cu/α-Al2O3 interfaces is
Kubilius, Jonas
2014-01-01
Sharing code is becoming increasingly important in the wake of Open Science. In this review I describe and compare two popular code-sharing utilities, GitHub and Open Science Framework (OSF). GitHub is a mature, industry-standard tool but lacks focus towards researchers. In comparison, OSF offers a one-stop solution for researchers but a lot of functionality is still under development. I conclude by listing alternative lesser-known tools for code and materials sharing.
CODING, ANALOG SYSTEMS), INFORMATION THEORY, DATA TRANSMISSION SYSTEMS , TRANSMITTER RECEIVERS, WHITE NOISE, PROBABILITY, ERRORS, PROBABILITY DENSITY FUNCTIONS, DIFFERENTIAL EQUATIONS, SET THEORY, COMPUTER PROGRAMS
Efficient quantum circuits for Szegedy quantum walks
Loke, T.; Wang, J. B.
2017-07-01
A major advantage in using Szegedy's formalism over discrete-time and continuous-time quantum walks lies in its ability to define a unitary quantum walk by quantizing a Markov chain on a directed or weighted graph. In this paper, we present a general scheme to construct efficient quantum circuits for Szegedy quantum walks that correspond to classical Markov chains possessing transformational symmetry in the columns of the transition matrix. In particular, the transformational symmetry criteria do not necessarily depend on the sparsity of the transition matrix, so this scheme can be applied to non-sparse Markov chains. Two classes of Markov chains that are amenable to this construction are cyclic permutations and complete bipartite graphs, for which we provide explicit efficient quantum circuit implementations. We also prove that our scheme can be applied to Markov chains formed by a tensor product. We also briefly discuss the implementation of Markov chains based on weighted interdependent networks. In addition, we apply this scheme to construct efficient quantum circuits simulating the Szegedy walks used in the quantum Pagerank algorithm for some classes of non-trivial graphs, providing a necessary tool for experimental demonstration of the quantum Pagerank algorithm.
The Mathematics of Error Correcting Quan tum Codes
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 6; Issue 4. The Mathematics of Error Correcting Quantum Codes - Quantum Coding. K R Parthasarathy. General Article Volume 6 Issue 4 April 2001 pp 38-51. Fulltext. Click here to view fulltext PDF. Permanent link:
Dokić, Jadranka; Gothe, Marcel; Wirth, Jonas; Peters, Maike V; Schwarz, Jutta; Hecht, Stefan; Saalfrank, Peter
2009-06-18
Quantum chemical calculations of various azobenzene (AB) derivatives have been carried out with the goal to describe the energetics and kinetics of their thermal cis --> trans isomerization. The effects of substituents, in particular their type, number, and positioning, on activation energies have been systematically studied with the ultimate goal to tailor the switching process. Trends observed for mono- and disubstituted species are discussed. A polarizable continuum model is used to study, in an approximate fashion, the cis --> trans isomerization of azobenzenes in solution. The nature of the transition state(s) and its dependence on substituents and the environment is discussed. In particular for push-pull azobenzenes, the reaction mechanism is found to change from inversion in nonpolar solvents to rotation in polar solvents. Concerning kinetics, calculations based on the Eyring transition state theory give usually reliable activation energies and enthalpies when compared to experimentally determined values. Also, trends in the resulting rate constants are correct. Other computed properties such as activation entropies and thus preexponential rate factors are in only moderate agreement with experiment.
Nakajima, Masakazu; Joester, Jenna A; Page, Nathan I; Reilly, Neil J; Bacskay, George B; Schmidt, Timothy W; Kable, Scott H
2009-07-28
A new band system of C(2), e (3)Pi(g)-c (3)Sigma(u)(+) was studied by ab initio quantum chemical and experimental methods. The calculations were carried out at the multireference configuration interaction level of theory with Davidson's correction using aug-cc-pV6Z basis set and include core and core-valence correlation as well as relativistic corrections computed with aug-cc-pCVQZ and cc-pVQZ bases, respectively. The vibrational energies and rotational constants of the upper e (3)Pi(g) state were calculated from the computed ab initio potential energy curve. The ab initio results indicate that the electronic transition moment of the e (3)Pi(g)-c (3)Sigma(u)(+) system is approximately one-half that of the Fox-Herzberg e (3)Pi(g)-a (3)Pi(u) system. Franck-Condon factors were calculated for both systems and used to guide experiments aimed at discovering the e (3)Pi(g)-c (3)Sigma(u)(+) system. The e (3)Pi(g)(v(') = 4)-c (3)Sigma(u)(+)(v(") = 3) band of jet-cooled C(2) was successfully observed by laser-induced fluorescence spectroscopy by monitoring the ensuing e (3)Pi(g)-a (3)Pi(u) emission.
Divergence coding for convolutional codes
Directory of Open Access Journals (Sweden)
Valery Zolotarev
2017-01-01
Full Text Available In the paper we propose a new coding/decoding on the divergence principle. A new divergent multithreshold decoder (MTD for convolutional self-orthogonal codes contains two threshold elements. The second threshold element decodes the code with the code distance one greater than for the first threshold element. Errorcorrecting possibility of the new MTD modification have been higher than traditional MTD. Simulation results show that the performance of the divergent schemes allow to approach area of its effective work to channel capacity approximately on 0,5 dB. Note that we include the enough effective Viterbi decoder instead of the first threshold element, the divergence principle can reach more. Index Terms — error-correcting coding, convolutional code, decoder, multithreshold decoder, Viterbi algorithm.
Thirumurugan, R.; Anitha, K.
2018-03-01
A novel organic proton transfer complex of imidazolium dipicolinate (ID) has been synthesized and it was grown as single crystals using slow evaporation method. The molecular structure of synthesized compound and vibrational modes of its functional groups were confirmed by (1H and 13C) NMR, FTIR and FT-Raman spectroscopic studies, respectively. Single crystal X-ray diffraction (SCXRD) analysis confirmed the orthorhombic system with noncentrosymmetric (NCS), P212121, space group of grown ID crystal. UV-Vis-NIR spectral study confirmed its high optical transparency within the region of 285-1500 nm. Powder second harmonic generation (SHG) efficiency of ID crystal was confirmed and it was 6.8 times that of KDP crystal. TG-DTA and DSC analysis revealed the higher thermal stability of grown crystal as 249 °C. The dielectric response and mechanical behaviour of grown crystal were studied effectively. Density functional theory calculations were performed to probe the relationship between the structure and its properties including molecular optimization, Mulliken atomic charge distribution, frontier molecular orbital (FMOs) and molecular electrostatic potential map (MEP) analysis and first hyperpolarizability. All these experimental and computational results were discussed in this communication and it endorsed the ID compound as a potential NLO candidate could be employed in optoelectronics device applications in near future.
Energy Technology Data Exchange (ETDEWEB)
Behler, Matthias; Hannstein, Volker; Kilger, Robert; Moser, Franz-Eberhard; Pfeiffer, Arndt; Stuke, Maik
2014-06-15
In order to account for the reactivity-reducing effect of burn-up in the criticality safety analysis for systems with irradiated nuclear fuel (''burnup credit''), numerical methods to determine the enrichment and burnup dependent nuclide inventory (''burnup code'') and its resulting multiplication factor k{sub eff} (''criticality code'') are applied. To allow for reliable conclusions, for both calculation systems the systematic deviations of the calculation results from the respective true values, the bias and its uncertainty, are being quantified by calculation and analysis of a sufficient number of suitable experiments. This quantification is specific for the application case under scope and is also called validation. GRS has developed a methodology to validate a calculation system for the application of burnup credit in the criticality safety analysis for irradiated fuel assemblies from pressurized water reactors. This methodology was demonstrated by applying the GRS home-built KENOREST burnup code and the criticality calculation sequence CSAS5 from SCALE code package. It comprises a bounding approach and alternatively a stochastic, which both have been exemplarily demonstrated by use of a generic spent fuel pool rack and a generic dry storage cask, respectively. Based on publicly available post irradiation examination and criticality experiments, currently the isotopes of uranium and plutonium elements can be regarded for.
DEFF Research Database (Denmark)
Cox, Geoff
Speaking Code begins by invoking the “Hello World” convention used by programmers when learning a new language, helping to establish the interplay of text and code that runs through the book. Interweaving the voice of critical writing from the humanities with the tradition of computing and software...... development, Speaking Code unfolds an argument to undermine the distinctions between criticism and practice, and to emphasize the aesthetic and political aspects of software studies. Not reducible to its functional aspects, program code mirrors the instability inherent in the relationship of speech......; alternatives to mainstream development, from performances of the live-coding scene to the organizational forms of commons-based peer production; the democratic promise of social media and their paradoxical role in suppressing political expression; and the market’s emptying out of possibilities for free...
Quantum error correction for beginners
Devitt, Simon J.; Munro, William J.; Nemoto, Kae
2013-07-01
Quantum error correction (QEC) and fault-tolerant quantum computation represent one of the most vital theoretical aspects of quantum information processing. It was well known from the early developments of this exciting field that the fragility of coherent quantum systems would be a catastrophic obstacle to the development of large-scale quantum computers. The introduction of quantum error correction in 1995 showed that active techniques could be employed to mitigate this fatal problem. However, quantum error correction and fault-tolerant computation is now a much larger field and many new codes, techniques, and methodologies have been developed to implement error correction for large-scale quantum algorithms. In response, we have attempted to summarize the basic aspects of quantum error correction and fault-tolerance, not as a detailed guide, but rather as a basic introduction. The development in this area has been so pronounced that many in the field of quantum information, specifically researchers who are new to quantum information or people focused on the many other important issues in quantum computation, have found it difficult to keep up with the general formalisms and methodologies employed in this area. Rather than introducing these concepts from a rigorous mathematical and computer science framework, we instead examine error correction and fault-tolerance largely through detailed examples, which are more relevant to experimentalists today and in the near future.
Energy Technology Data Exchange (ETDEWEB)
Kozmenkov, Y. [Helmholtz-Zentrum Dresden-Rossendorf e.V. (FZD), Institute of Safety Research, P.O.B. 510119, D-01324 Dresden (Germany); Institute of Physics and Power Engineering, Obninsk (Russian Federation); Rohde, U., E-mail: U.Rohde@hzdr.de [Helmholtz-Zentrum Dresden-Rossendorf e.V. (FZD), Institute of Safety Research, P.O.B. 510119, D-01324 Dresden (Germany); Manera, A. [Paul Scherrer Institute (Switzerland)
2012-02-15
Highlights: Black-Right-Pointing-Pointer We report about the simulation of flashing-induced instabilities in natural circulation systems. Black-Right-Pointing-Pointer Flashing-induced instabilities are of relevance for operation of pool-type reactors of small power at low pressure. Black-Right-Pointing-Pointer The RELAP5 code is validated against measurement data from natural circulation experiments. Black-Right-Pointing-Pointer The magnitude and frequency of the oscillations were reproduced in good agreement with the measurement data. - Abstract: This paper reports on the use of the RELAP5 code for the simulation of flashing-induced instabilities in natural circulation systems. The RELAP 5 code is intended to be used for the simulation of transient processes in the Russian RUTA reactor concept operating at atmospheric pressure with forced convection of coolant. However, during transient processes, natural circulation with flashing-induced instabilities might occur. The RELAP5 code is validated against measurement data from natural circulation experiments performed within the framework of a European project (NACUSP) on the CIRCUS facility. The facility, built at the Delft University of Technology in The Netherlands, is a water/steam 1:1 height-scaled loop of a typical natural-circulation-cooled BWR. It was shown that the RELAP5 code is able to model all relevant phenomena related to flashing induced instabilities. The magnitude and frequency of the oscillations were reproduced in a good agreement with the measurement data. The close correspondence to the experiments was reached by detailed modeling of all components of the CIRCUS facility including the heat exchanger, the buffer vessel and the steam dome at the top of the facility.
Korkmaz, Ufuk; Topçu, Yıldıray; Taş, Murat; Bulut, Ahmet
2015-01-05
The experimental and theoretical investigation results of a novel organic squarate salt of 4-Morpholinium bis(hydrogen squarate) (1), C₆H₁₄ON(+)·C₈H₃O₈(-), were reported in this study. The crystal structure of the title compound was found to crystallize in the triclinic P-1 space group. In the crystals of 1 the morpholine ring adopts the chair conformation with the ethyl group in the equatorial and hydrogen atoms in axial positions. The hydrogen squarate anions are linked into a homoconjugated anion, [(HSQ)₂H], by a short symmetric, nonlinear O₈⋯H₂⋯O₂ hydrogen bond of 2.444 (2)Å. The structural and vibrational properties of the compound were also studied by computational methods of ab-initio performed on the compound at DFT/B3LYP/6-31++G(d,p) (2) and HF/6-31++G(d,p) (3) level of theory. The obtained calculation results on the basis of two models for both the optimized molecular structure and vibrational properties for the 1 obtained are presented and compared with the X-ray analysis result. On the other hand the molecular electrostatic potential (MEP), electronic absorption spectra, frontier molecular orbitals (FMOs), conformational flexibility and non-linear optical properties (NLO) of the title compound were also studied at the 2 level and the results are reported. In order to evaluate the suitability for NLO applications thermal analysis (TG, DTA and DTG) data of 1 were also obtained. Copyright © 2014 Elsevier B.V. All rights reserved.
Multiple LDPC decoding for distributed source coding and video coding
DEFF Research Database (Denmark)
Forchhammer, Søren; Luong, Huynh Van; Huang, Xin
2011-01-01
Distributed source coding (DSC) is a coding paradigm for systems which fully or partly exploit the source statistics at the decoder to reduce the computational burden at the encoder. Distributed video coding (DVC) is one example. This paper considers the use of Low Density Parity Check Accumulate...... (LDPCA) codes in a DSC scheme with feed-back. To improve the LDPC coding performance in the context of DSC and DVC, while retaining short encoder blocks, this paper proposes multiple parallel LDPC decoding. The proposed scheme passes soft information between decoders to enhance performance. Experimental...
High-dimensional quantum cloning and applications to quantum hacking.
Bouchard, Frédéric; Fickler, Robert; Boyd, Robert W; Karimi, Ebrahim
2017-02-01
Attempts at cloning a quantum system result in the introduction of imperfections in the state of the copies. This is a consequence of the no-cloning theorem, which is a fundamental law of quantum physics and the backbone of security for quantum communications. Although perfect copies are prohibited, a quantum state may be copied with maximal accuracy via various optimal cloning schemes. Optimal quantum cloning, which lies at the border of the physical limit imposed by the no-signaling theorem and the Heisenberg uncertainty principle, has been experimentally realized for low-dimensional photonic states. However, an increase in the dimensionality of quantum systems is greatly beneficial to quantum computation and communication protocols. Nonetheless, no experimental demonstration of optimal cloning machines has hitherto been shown for high-dimensional quantum systems. We perform optimal cloning of high-dimensional photonic states by means of the symmetrization method. We show the universality of our technique by conducting cloning of numerous arbitrary input states and fully characterize our cloning machine by performing quantum state tomography on cloned photons. In addition, a cloning attack on a Bennett and Brassard (BB84) quantum key distribution protocol is experimentally demonstrated to reveal the robustness of high-dimensional states in quantum cryptography.
National software infrastructure for lattice quantum chromodynamics
Energy Technology Data Exchange (ETDEWEB)
Brower, R C; DeTar, C E; Edwards, R G; Holmgren, Donald J; Mawhinney, R D; Watson, W; Zhang, Y
2006-06-01
Quantum chromodynamics (QCD) is the widely accepted theory of the strong interactions of quarks and gluons. Only through large scale numerical simulation has it been possible to work out the predictions of this theory for a vast range of phenomena relevant to the US Department of Energy experimental program. Such simulations are essential to support the discovery of new phenomena and more fundamental interactions. With support from SciDAC the USQCD collaboration has developed software and prototyped custom computer hardware to carry out the required numerical simulations. We have developed a robust, portable data-parallel code suite. It provides a user-friendly basis for writing physics application codes for carrying out the calculations needed to predict the phenomenology of QCD. We are using this efficient and optimized code base to develop new physics application code, to improve the performance of legacy code, and to construct higher level tools, such as QCD-specific sparse matrix solvers. We give a brief overview of the design of the data parallel API and its various components. We describe performance gains achieved in the past year. Finally, we present plans for further improvements under SciDAC-2.
Optical quantum memory based on electromagnetically induced transparency.
Ma, Lijun; Slattery, Oliver; Tang, Xiao
2017-04-01
Electromagnetically induced transparency (EIT) is a promising approach to implement quantum memory in quantum communication and quantum computing applications. In this paper, following a brief overview of the main approaches to quantum memory, we provide details of the physical principle and theory of quantum memory based specifically on EIT. We discuss the key technologies for implementing quantum memory based on EIT and review important milestones, from the first experimental demonstration to current applications in quantum information systems.
Computer Code for Nanostructure Simulation
Filikhin, Igor; Vlahovic, Branislav
2009-01-01
Due to their small size, nanostructures can have stress and thermal gradients that are larger than any macroscopic analogue. These gradients can lead to specific regions that are susceptible to failure via processes such as plastic deformation by dislocation emission, chemical debonding, and interfacial alloying. A program has been developed that rigorously simulates and predicts optoelectronic properties of nanostructures of virtually any geometrical complexity and material composition. It can be used in simulations of energy level structure, wave functions, density of states of spatially configured phonon-coupled electrons, excitons in quantum dots, quantum rings, quantum ring complexes, and more. The code can be used to calculate stress distributions and thermal transport properties for a variety of nanostructures and interfaces, transport and scattering at nanoscale interfaces and surfaces under various stress states, and alloy compositional gradients. The code allows users to perform modeling of charge transport processes through quantum-dot (QD) arrays as functions of inter-dot distance, array order versus disorder, QD orientation, shape, size, and chemical composition for applications in photovoltaics and physical properties of QD-based biochemical sensors. The code can be used to study the hot exciton formation/relation dynamics in arrays of QDs of different shapes and sizes at different temperatures. It also can be used to understand the relation among the deposition parameters and inherent stresses, strain deformation, heat flow, and failure of nanostructures.
Quantum Computation and Information From Theory to Experiment
Imai, Hiroshi
2006-01-01
Recently, the field of quantum computation and information has been developing through a fusion of results from various research fields in theoretical and practical areas. This book consists of the reviews of selected topics charterized by great progress and cover the field from theoretical areas to experimental ones. It contains fundamental areas, quantum query complexity, quantum statistical inference, quantum cloning, quantum entanglement, additivity. It treats three types of quantum security system, quantum public key cryptography, quantum key distribution, and quantum steganography. A photonic system is highlighted for the realization of quantum information processing.
Quantum computing on encrypted data.
Fisher, K A G; Broadbent, A; Shalm, L K; Yan, Z; Lavoie, J; Prevedel, R; Jennewein, T; Resch, K J
2014-01-01
The ability to perform computations on encrypted data is a powerful tool for protecting privacy. Recently, protocols to achieve this on classical computing systems have been found. Here, we present an efficient solution to the quantum analogue of this problem that enables arbitrary quantum computations to be carried out on encrypted quantum data. We prove that an untrusted server can implement a universal set of quantum gates on encrypted quantum bits (qubits) without learning any information about the inputs, while the client, knowing the decryption key, can easily decrypt the results of the computation. We experimentally demonstrate, using single photons and linear optics, the encryption and decryption scheme on a set of gates sufficient for arbitrary quantum computations. As our protocol requires few extra resources compared with other schemes it can be easily incorporated into the design of future quantum servers. These results will play a key role in enabling the development of secure distributed quantum systems.
Belief propagation decoding of quantum channels by passing quantum messages
Renes, Joseph M.
2017-07-01
The belief propagation (BP) algorithm is a powerful tool in a wide range of disciplines from statistical physics to machine learning to computational biology, and is ubiquitous in decoding classical error-correcting codes. The algorithm works by passing messages between nodes of the factor graph associated with the code and enables efficient decoding of the channel, in some cases even up to the Shannon capacity. Here we construct the first BP algorithm which passes quantum messages on the factor graph and is capable of decoding the classical-quantum channel with pure state outputs. This gives explicit decoding circuits whose number of gates is quadratic in the code length. We also show that this decoder can be modified to work with polar codes for the pure state channel and as part of a decoder for transmitting quantum information over the amplitude damping channel. These represent the first explicit capacity-achieving decoders for non-Pauli channels.
DEFF Research Database (Denmark)
Johansen, Jeppe; Stobbe, Søren; Nikolaev, I.S.
2007-01-01
We have measured time-resolved spontaneous emission from quantum dots near a dielectric interface with known photonic local density of states. We thus experimentally determine the quantum efficiency and the dipole moment, important for quantum optics.......We have measured time-resolved spontaneous emission from quantum dots near a dielectric interface with known photonic local density of states. We thus experimentally determine the quantum efficiency and the dipole moment, important for quantum optics....
Directory of Open Access Journals (Sweden)
Frisoni Manuela
2017-01-01
Full Text Available ANITA-IEAF is an activation package (code and libraries developed in the past in ENEA-Bologna in order to assess the activation of materials exposed to neutrons with energies greater than 20 MeV. An updated version of the ANITA-IEAF activation code package has been developed. It is suitable to be applied to the study of the irradiation effects on materials in facilities like the International Fusion Materials Irradiation Facility (IFMIF and the DEMO Oriented Neutron Source (DONES, in which a considerable amount of neutrons with energies above 20 MeV is produced. The present paper summarizes the main characteristics of the updated version of ANITA-IEAF, able to use decay and cross section data based on more recent evaluated nuclear data libraries, i.e. the JEFF-3.1.1 Radioactive Decay Data Library and the EAF-2010 neutron activation cross section library. In this paper the validation effort related to the comparison between the code predictions and the activity measurements obtained from the Karlsruhe Isochronous Cyclotron is presented. In this integral experiment samples of two different steels, SS-316 and F82H, pure vanadium and a vanadium alloy, structural materials of interest in fusion technology, were activated in a neutron spectrum similar to the IFMIF neutron field.
Frisoni, Manuela
2017-09-01
ANITA-IEAF is an activation package (code and libraries) developed in the past in ENEA-Bologna in order to assess the activation of materials exposed to neutrons with energies greater than 20 MeV. An updated version of the ANITA-IEAF activation code package has been developed. It is suitable to be applied to the study of the irradiation effects on materials in facilities like the International Fusion Materials Irradiation Facility (IFMIF) and the DEMO Oriented Neutron Source (DONES), in which a considerable amount of neutrons with energies above 20 MeV is produced. The present paper summarizes the main characteristics of the updated version of ANITA-IEAF, able to use decay and cross section data based on more recent evaluated nuclear data libraries, i.e. the JEFF-3.1.1 Radioactive Decay Data Library and the EAF-2010 neutron activation cross section library. In this paper the validation effort related to the comparison between the code predictions and the activity measurements obtained from the Karlsruhe Isochronous Cyclotron is presented. In this integral experiment samples of two different steels, SS-316 and F82H, pure vanadium and a vanadium alloy, structural materials of interest in fusion technology, were activated in a neutron spectrum similar to the IFMIF neutron field.
Hartle, James B.
2018-01-01
A quantum theory of the universe consists of a theory of its quantum dynamics and a theory of its quantum state The theory predicts quantum multiverses in the form of decoherent sets of alternative histories describing the evolution of the universe's spacetime geometry and matter content. These consequences follow: (a) The universe generally exhibits different quantum multiverses at different levels and kinds of coarse graining. (b) Quantum multiverses are not a choice or an assumption but ar...
Traub, Joseph F.
2014-01-01
The aim of this thesis was to explain what quantum computing is. The information for the thesis was gathered from books, scientific publications, and news articles. The analysis of the information revealed that quantum computing can be broken down to three areas: theories behind quantum computing explaining the structure of a quantum computer, known quantum algorithms, and the actual physical realizations of a quantum computer. The thesis reveals that moving from classical memor...
Directory of Open Access Journals (Sweden)
Anthony McCosker
2014-03-01
Full Text Available As well as introducing the Coding Labour section, the authors explore the diffusion of code across the material contexts of everyday life, through the objects and tools of mediation, the systems and practices of cultural production and organisational management, and in the material conditions of labour. Taking code beyond computation and software, their specific focus is on the increasingly familiar connections between code and labour with a focus on the codification and modulation of affect through technologies and practices of management within the contemporary work organisation. In the grey literature of spreadsheets, minutes, workload models, email and the like they identify a violence of forms through which workplace affect, in its constant flux of crisis and ‘prodromal’ modes, is regulated and governed.
National Research Council Canada - National Science Library
McCosker, Anthony; Milne, Esther
2014-01-01
... software. Code encompasses the laws that regulate human affairs and the operation of capital, behavioural mores and accepted ways of acting, but it also defines the building blocks of life as DNA...
Nonlinear Dynamics In Quantum Physics -- Quantum Chaos and Quantum Instantons
Kröger, H.
2003-01-01
We discuss the recently proposed quantum action - its interpretation, its motivation, its mathematical properties and its use in physics: quantum mechanical tunneling, quantum instantons and quantum chaos.
Quantum information with Rydberg atoms
DEFF Research Database (Denmark)
Saffman, Mark; Walker, T.G.; Mølmer, Klaus
2010-01-01
Rydberg atoms with principal quantum number n»1 have exaggerated atomic properties including dipole-dipole interactions that scale as n4 and radiative lifetimes that scale as n3. It was proposed a decade ago to take advantage of these properties to implement quantum gates between neutral atom...... of multiqubit registers, implementation of robust light-atom quantum interfaces, and the potential for simulating quantum many-body physics. The advances of the last decade are reviewed, covering both theoretical and experimental aspects of Rydberg-mediated quantum information processing....
Le, Quang Anh Tuan; Kim, Seonghoon; Chang, Rakwoo; Kim, Yong Hwan
2015-07-30
Serum paraoxonase 1 (PON1) is a versatile enzyme for the hydrolysis of various substrates (e.g., lactones, phosphotriesters) and for the formation of a promising chemical platform γ-valerolactone. Elucidation of the PON1-catalyzed lactonase reaction mechanism is very important for understanding the enzyme function and for engineering this enzyme for specific applications. Kinetic study and hybrid quantum mechanics/molecular mechanics (QM/MM) method were used to investigate the PON1-catalyzed lactonase reaction of γ-butyrolactone (GBL) and (R)-γ-valerolactone (GVL). The activation energies obtained from the QM/MM calculations were in good agreement with the experiments. Interestingly, the QM/MM energy barriers at MP2/3-21G(d,p) level for the lactonase of GVL and GBL were respectively 14.3-16.2 and 11.5-13.1 kcal/mol, consistent with the experimental values (15.57 and 14.73 kcal/mol derived from respective kcat values of 36.62 and 147.21 s(-1)). The QM/MM energy barriers at MP2/6-31G(d) and MP2/6-31G(d,p) levels were also in relatively good agreements with the experiments. Importantly, the difference in the QM/MM energy barriers at MP2 level with all investigated basis sets for the lactonase of GVL and GBL were in excellent agreement with the experiments (0.9-3.1 and 0.8 kcal/mol, respectively). A detailed mechanism for the PON1-catalyzed lactonase reaction was also proposed in this study.
Quantum Communication with Photons
Krenn, Mario; Malik, Mehul; Scheidl, Thomas; Ursin, Rupert; Zeilinger, Anton
The secure communication of information plays an ever increasing role in our society today. Classical methods of encryption inherently rely on the difficulty of solving a problem such as finding prime factors of large numbers and can, in principle, be cracked by a fast enough machine. The burgeoning field of quantum communication relies on the fundamental laws of physics to offer unconditional information security. Here we introduce the key concepts of quantum superposition and entanglement as well as the no-cloning theorem that form the basis of this field. Then, we review basic quantum communication schemes with single and entangled photons and discuss recent experimental progress in ground and space-based quantum communication. Finally, we discuss the emerging field of high-dimensional quantum communication, which promises increased data rates and higher levels of security than ever before. We discuss recent experiments that use the orbital angular momentum of photons for sharing large amounts of information in a secure fashion.
Li, Ying; Holloway, Gregory W.; Benjamin, Simon C.; Briggs, G. Andrew D.; Baugh, Jonathan; Mol, Jan A.
2017-08-01
Memristive systems are generalizations of memristors, which are resistors with memory. In this paper, we present a quantum description of quantum dot memristive systems. Using this model we propose and experimentally demonstrate a simple and practical scheme for realizing memristive systems with quantum dots. The approach harnesses a phenomenon that is commonly seen as a bane of nanoelectronics, i.e., switching of a trapped charge in the vicinity of the device. We show that quantum dot memristive systems have hysteresis current-voltage characteristics and quantum jump-induced stochastic behavior. While our experiment requires low temperatures, the same setup could, in principle, be realized with a suitable single-molecule transistor and operated at or near room temperature.
Surface code implementation of block code state distillation
Fowler, Austin G.; Devitt, Simon J.; Jones, Cody
2013-01-01
State distillation is the process of taking a number of imperfect copies of a particular quantum state and producing fewer better copies. Until recently, the lowest overhead method of distilling states produced a single improved |A〉 state given 15 input copies. New block code state distillation methods can produce k improved |A〉 states given 3k + 8 input copies, potentially significantly reducing the overhead associated with state distillation. We construct an explicit surface code implementation of block code state distillation and quantitatively compare the overhead of this approach to the old. We find that, using the best available techniques, for parameters of practical interest, block code state distillation does not always lead to lower overhead, and, when it does, the overhead reduction is typically less than a factor of three. PMID:23736868
Multiphoton quantum optics and quantum state engineering
Energy Technology Data Exchange (ETDEWEB)
Dell' Anno, Fabio [Dipartimento di Fisica ' E. R. Caianiello' , Universita degli Studi di Salerno, CNISM and CNR-INFM Coherentia, and INFN Sezione di Napoli, Gruppo Collegato di Salerno, Via S. Allende, I-84081 Baronissi (Saudi Arabia) (Italy)]. E-mail: dellanno@sa.infn.it; De Siena, Silvio [Dipartimento di Fisica ' E. R. Caianiello' , Universita degli Studi di Salerno, CNISM and CNR-INFM Coherentia, and INFN Sezione di Napoli, Gruppo Collegato di Salerno, Via S. Allende, I-84081 Baronissi (SA) (Italy)]. E-mail: desiena@sa.infn.it; Illuminati, Fabrizio [Dipartimento di Fisica ' E. R. Caianiello' , Universita degli Studi di Salerno, CNISM and CNR-INFM Coherentia, and INFN Sezione di Napoli, Gruppo Collegato di Salerno, Via S. Allende, I-84081 Baronissi (SA) (Italy)]. E-mail: illuminati@sa.infn.it
2006-05-15
We present a review of theoretical and experimental aspects of multiphoton quantum optics. Multiphoton processes occur and are important for many aspects of matter-radiation interactions that include the efficient ionization of atoms and molecules, and, more generally, atomic transition mechanisms; system-environment couplings and dissipative quantum dynamics; laser physics, optical parametric processes, and interferometry. A single review cannot account for all aspects of such an enormously vast subject. Here we choose to concentrate our attention on parametric processes in nonlinear media, with special emphasis on the engineering of nonclassical states of photons and atoms that are relevant for the conceptual investigations as well as for the practical applications of forefront aspects of modern quantum mechanics. We present a detailed analysis of the methods and techniques for the production of genuinely quantum multiphoton processes in nonlinear media, and the corresponding models of multiphoton effective interactions. We review existing proposals for the classification, engineering, and manipulation of nonclassical states, including Fock states, macroscopic superposition states, and multiphoton generalized coherent states. We introduce and discuss the structure of canonical multiphoton quantum optics and the associated one- and two-mode canonical multiphoton squeezed states. This framework provides a consistent multiphoton generalization of two-photon quantum optics and a consistent Hamiltonian description of multiphoton processes associated to higher-order nonlinearities. Finally, we discuss very recent advances that by combining linear and nonlinear optical devices allow to realize multiphoton entangled states of the electromagnetic field, either in discrete or in continuous variables, that are relevant for applications to efficient quantum computation, quantum teleportation, and related problems in quantum communication and information.
Enhanced sensing and communication via quantum networks
Smith, James F.
2017-05-01
A network based on quantum information has been developed to improve sensing and communications capabilities. Quantum teleportation offers features for communicating information not found in classical procedures. It is fundamental to the quantum network approach. A version of quantum teleportation based on hyper-entanglement is used to bring about these improvements. Recently invented methods of improving sensing and communication via quantum information based on hyper-entanglement are discussed. These techniques offer huge improvements in the SNR, signal to interference ratio, and time-on-target of various sensors including RADAR and LADAR. Hyper-entanglement refers to quantum entanglement in more than one degree of freedom, e.g. polarization, energy-time, orbital angular momentum (OAM), etc. The quantum network makes use of quantum memory located in each node of the network, thus the network forms a quantum repeater. The quantum repeater facilitates the use of quantum teleportation, and superdense coding. Superdense coding refers to the ability to incorporate more than one classical bit into each transmitted qubit. The network of sensors and/or communication devices has an enhanced resistance to interference sources. The repeater has the potential for greatly reducing loss in communications and sensor systems related to the effect of the atmosphere on fragile quantum states. Measures of effectiveness (MOEs) are discussed that show the utility of the network for improving sensing and communications in the presence of loss and noise. The quantum repeater will reduce overall size, weight, power and cost (SWAPC) of fielded components of systems.
Energy Technology Data Exchange (ETDEWEB)
Ravishankar, C., Hughes Network Systems, Germantown, MD
1998-05-08
Speech is the predominant means of communication between human beings and since the invention of the telephone by Alexander Graham Bell in 1876, speech services have remained to be the core service in almost all telecommunication systems. Original analog methods of telephony had the disadvantage of speech signal getting corrupted by noise, cross-talk and distortion Long haul transmissions which use repeaters to compensate for the loss in signal strength on transmission links also increase the associated noise and distortion. On the other hand digital transmission is relatively immune to noise, cross-talk and distortion primarily because of the capability to faithfully regenerate digital signal at each repeater purely based on a binary decision. Hence end-to-end performance of the digital link essentially becomes independent of the length and operating frequency bands of the link Hence from a transmission point of view digital transmission has been the preferred approach due to its higher immunity to noise. The need to carry digital speech became extremely important from a service provision point of view as well. Modem requirements have introduced the need for robust, flexible and secure services that can carry a multitude of signal types (such as voice, data and video) without a fundamental change in infrastructure. Such a requirement could not have been easily met without the advent of digital transmission systems, thereby requiring speech to be coded digitally. The term Speech Coding is often referred to techniques that represent or code speech signals either directly as a waveform or as a set of parameters by analyzing the speech signal. In either case, the codes are transmitted to the distant end where speech is reconstructed or synthesized using the received set of codes. A more generic term that is applicable to these techniques that is often interchangeably used with speech coding is the term voice coding. This term is more generic in the sense that the
Achieving the Heisenberg limit in quantum metrology using quantum error correction.
Zhou, Sisi; Zhang, Mengzhen; Preskill, John; Jiang, Liang
2018-01-08
Quantum metrology has many important applications in science and technology, ranging from frequency spectroscopy to gravitational wave detection. Quantum mechanics imposes a fundamental limit on measurement precision, called the Heisenberg limit, which can be achieved for noiseless quantum systems, but is not achievable in general for systems subject to noise. Here we study how measurement precision can be enhanced through quantum error correction, a general method for protecting a quantum system from the damaging effects of noise. We find a necessary and sufficient condition for achieving the Heisenberg limit using quantum probes subject to Markovian noise, assuming that noiseless ancilla systems are available, and that fast, accurate quantum processing can be performed. When the sufficient condition is satisfied, a quantum error-correcting code can be constructed that suppresses the noise without obscuring the signal; the optimal code, achieving the best possible precision, can be found by solving a semidefinite program.
Güçlü, Alev Devrim; Korkusinski, Marek; Hawrylak, Pawel
2014-01-01
This book reflects the current status of theoretical and experimental research of graphene based nanostructures, in particular quantum dots, at a level accessible to young researchers, graduate students, experimentalists and theorists. It presents the current state of research of graphene quantum dots, a single or few monolayer thick islands of graphene. It introduces the reader to the electronic and optical properties of graphite, intercalated graphite and graphene, including Dirac fermions, Berry's phase associated with sublattices and valley degeneracy, covers single particle properties of
Decoherence and quantum measurements
Namiki, Mikio; Pascazio, Saverio
1997-01-01
The quantum measurement problem is one of the most fascinating and challenging topics in physics both theoretically and experimentally. It involves deep questions and the use of very sophisticated and elegant techniques. After analyzing the fundamental principles of quantum mechanics and of the Copenhagen interpretation, this book reviews the most important approaches to the measurement problem and rigorously reformulates the "collapse of the wave function" by measurement, as a dephasing process quantitatively characterized by an order parameter (called the decoherence parameter), according to
Hosten, O.; Krishnakumar, R.; Engelsen, N. J.; Kasevich, M.A.
2016-01-01
Quantum metrology exploits entangled states of particles to improve sensing precision beyond the limit achievable with uncorrelated particles. All previous methods required detection noise levels below this standard quantum limit to realize the benefits of the intrinsic sensitivity provided by these states. Remarkably, a recent proposal has shown that, in principle, such low-noise detection is not a necessary requirement. Here, we experimentally demonstrate a widely applicable method for enta...
Fialko, O; Hallwood, D W
2012-02-24
We present a theoretical and numerical analysis of a quantum system that is capable of functioning as a heat engine. This system could be realized experimentally using cold bosonic atoms confined to a double well potential that is created by splitting a harmonic trap with a focused laser. The system shows thermalization, and can model a reversible heat engine cycle. This is the first demonstration of the operation of a heat engine with a finite quantum heat bath.
Fialko, O.; Hallwood, D.
2011-01-01
We present a theoretical and numerical analysis of a quantum system that is capable of functioning as a heat engine. This system could be realized experimentally using cold bosonic atoms confined to a double well potential that is created by splitting a harmonic trap with a focused laser. The system shows thermalization, and can model a reversible heat engine cycle. This is the first demonstration of the operation of a heat engine with a finite quantum heat bath.
Wu, Jiang
2013-01-01
The third generation of solar cells includes those based on semiconductor quantum dots. This sophisticated technology applies nanotechnology and quantum mechanics theory to enhance the performance of ordinary solar cells. Although a practical application of quantum dot solar cells has yet to be achieved, a large number of theoretical calculations and experimental studies have confirmed the potential for meeting the requirement for ultra-high conversion efficiency. In this book, high-profile scientists have contributed tutorial chapters that outline the methods used in and the results of variou
Weiss, Ulrich
2008-01-01
Major advances in the quantum theory of macroscopic systems, in combination with stunning experimental achievements, have brightened the field and brought it to the attention of the general community in natural sciences. Today, working knowledge of dissipative quantum mechanics is an essential tool for many physicists. This book - originally published in 1990 and republished in 1999 as an enlarged second edition - delves much deeper than ever before into the fundamental concepts, methods, and applications of quantum dissipative systems, including the most recent developments. In this third edi
di Candia, Roberto; Mejia, Bernabé; Castillo, Hernan; Simon Pedernales, Julen; Casanova, Jorge; Solano, Enrique
2014-03-01
We introduce the concept of embedding quantum simulator, a paradigm allowing efficient computation of dynamical quantities requiring full quantum tomography in a standard quantum simulator (one-to-one quantum simulator). The concept consists in the suitable encoding of a simulated quantum dynamics in the enlarged Hilbert space of an embedding quantum simulator. In this manner, non-trivial quantities are mapped onto physical observables, overcoming the necessity of full tomography, and reducing drastically the experimental requirements. As examples, we discuss how to evaluate entanglement monotones and time correlation functions, each in a suitable embedding quantum simulator. Finally, we expect that the proposed embedding framework paves the way for a general theory of enhanced one-to-one quantum simulators. This work is supported by Spanish MINECO FIS2012-36673-C03-02; UPV/EHU UFI 11/55; UPV/EHU PhD fellowship; Basque Government IT472-10; SOLID, CCQED, PROMISCE, SCALEQIT EU projects; and Marco Polo PUCP grant.
Quantum cryptography communication technology
Energy Technology Data Exchange (ETDEWEB)
Cho, Jai Wan; Choi, Young Soo; Lee, Jae Chul; Choi, Yu Rak; Jung, Gwang Il; Jung, Jong Eun; Hong, Seok Boong; Koo, In Soo
2007-09-15
Quantum cryptography communication based on quantum mechanics provides and unconditional security between two users. Even though huge advance has been done since the 1984, having a complete system is still far away. In the case of real quantum cryptography communication systems, an unconditional security level is lowered by the imperfection of the communication unit. It is important to investigate the unconditional security of quantum communication protocols based on these experimental results and implementation examples for the advanced spread all over the world. The Japanese report, titled, 'Investigation report on the worldwide trends of quantum cryptography communications systems' was translated and summarized in this report. An unconditional security theory of the quantum cryptography and real implementation examples in the domestic area are investigated also. The goal of the report is to make quantum cryptography communication more useful and reliable alternative telecommunication infrastructure as the one of the cyber security program of the class 1-E communication system of nuclear power plant. Also another goal of this report is to provide the quantitative decision basis on the quantum cryptography communication when this secure communication system will be used in class 1-E communication channel of the nuclear power plant.
Introduction to the theory of quantum information processing
Bergou, János A
2013-01-01
Introduction to the Theory of Quantum Information Processing provides the material for a one-semester graduate level course on quantum information theory and quantum computing for students who have had a one-year graduate course in quantum mechanics. Many standard subjects are treated, such as density matrices, entanglement, quantum maps, quantum cryptography, and quantum codes. Also included are discussions of quantum machines and quantum walks. In addition, the book provides detailed treatments of several underlying fundamental principles of quantum theory, such as quantum measurements, the no-cloning and no-signaling theorems, and their consequences. Problems of various levels of difficulty supplement the text, with the most challenging problems bringing the reader to the forefront of active research. This book provides a compact introduction to the fascinating and rapidly evolving interdisciplinary field of quantum information theory, and it prepares the reader for doing active research in this area.
Playing distributed two-party quantum games on quantum networks
Liu, Bo-Yang; Dai, Hong-Yi; Zhang, Ming
2017-12-01
This paper investigates quantum games between two remote players on quantum networks. We propose two schemes for distributed remote quantum games: the client-server scheme based on states transmission between nodes of the network and the peer-to-peer scheme devised upon remote quantum operations. Following these schemes, we construct two designs of the distributed prisoners' dilemma game on quantum entangling networks, where concrete methods are employed for teleportation and nonlocal two-qubits unitary gates, respectively. It seems to us that the requirement for playing distributed quantum games on networks is still an open problem. We explore this problem by comparing and characterizing the two schemes from the viewpoints of network structures, quantum and classical operations, experimental realization and simplification.
Quantum cloning attacks against PUF-based quantum authentication systems
Yao, Yao; Gao, Ming; Li, Mo; Zhang, Jian
2016-08-01
With the advent of physical unclonable functions (PUFs), PUF-based quantum authentication systems have been proposed for security purposes, and recently, proof-of-principle experiment has been demonstrated. As a further step toward completing the security analysis, we investigate quantum cloning attacks against PUF-based quantum authentication systems and prove that quantum cloning attacks outperform the so-called challenge-estimation attacks. We present the analytical expression of the false-accept probability by use of the corresponding optimal quantum cloning machines and extend the previous results in the literature. In light of these findings, an explicit comparison is made between PUF-based quantum authentication systems and quantum key distribution protocols in the context of cloning attacks. Moreover, from an experimental perspective, a trade-off between the average photon number and the detection efficiency is discussed in detail.
Lanzagorta, Marco
2011-01-01
This book offers a concise review of quantum radar theory. Our approach is pedagogical, making emphasis on the physics behind the operation of a hypothetical quantum radar. We concentrate our discussion on the two major models proposed to date: interferometric quantum radar and quantum illumination. In addition, this book offers some new results, including an analytical study of quantum interferometry in the X-band radar region with a variety of atmospheric conditions, a derivation of a quantum radar equation, and a discussion of quantum radar jamming.This book assumes the reader is familiar w
Energy Technology Data Exchange (ETDEWEB)
Muramatsu, Toshiharu [Power Reactor and Nuclear Fuel Development Corp., Oarai, Ibaraki (Japan). Oarai Engineering Center
1997-06-01
A benchmark exercise on `Tee junction of Liquid Metal Fast Reactor (LMFR) secondary circuit` was proposed by France in the scope of the said Coordinated Research Program (CRP) via International Atomic Energy Agency (IAEA). The physical phenomenon chosen here deals with the mixture of two flows of different temperature. In a LMFR, several areas of the reactor are submitted to this problem. They are often difficult to design, because of the complexity of the phenomena involved. This is one of the major problems of the LMFRs. This problem has been encountered in the Phenix reactor on the secondary loop, where defects in a tee junction zone were detected during a campaign of inspections after an operation of 90,000 hours of the reactor. The present benchmark is based on an industrial problem and deal with thermal striping phenomena. Problems on pipes induced by thermal striping phenomena have been observed in some reactors and experimental facilities coolant circuits. This report presents numerical results on thermohydraulic characteristics of the benchmark problem, carried out using a direct numerical simulation code DINUS-3 and a boundary element code BEMSET. From the analysis with both the codes, it was confirmed that the hot sodium from the small pipe rise into the cold sodium of the main pipe with thermally instabilities. Furthermore, it was indicated that the coolant mixing region including the instabilities agrees approximately with the result by eye inspections. (author)
Directory of Open Access Journals (Sweden)
Robert Root-Bernstein
2010-06-01
Full Text Available L-amino acids bind preferentially to their D-codons, but almost nothing is known about whether D-amino acids correspondingly prefer L-codons, or how codon directionality affects amino acid binding. To investigate these issues, two D-RNA-oligonucleotides having inverse base sequences (D-CGUA and D-AUGC and their corresponding L-RNA-oligonucleotides (L-CGUA and L-AUGC were synthesized and their affinity determined for Gly and eleven pairs of L- and D-amino acids. The data support the hypothesis (Root-Bernstein, Bioessays 2007; 29: 689–698 that homochirality and codon directionality emerged as a function of the origin of the genetic code itself. Further tests involving amplification methods are proposed.
Energy Technology Data Exchange (ETDEWEB)
Delbecq, J.M
1999-07-01
The Aster code is a 2D or 3D finite-element calculation code for structures developed by the R and D direction of Electricite de France (EdF). This dossier presents a complete overview of the characteristics and uses of the Aster code: introduction of version 4; the context of Aster (organisation of the code development, versions, systems and interfaces, development tools, quality assurance, independent validation); static mechanics (linear thermo-elasticity, Euler buckling, cables, Zarka-Casier method); non-linear mechanics (materials behaviour, big deformations, specific loads, unloading and loss of load proportionality indicators, global algorithm, contact and friction); rupture mechanics (G energy restitution level, restitution level in thermo-elasto-plasticity, 3D local energy restitution level, KI and KII stress intensity factors, calculation of limit loads for structures), specific treatments (fatigue, rupture, wear, error estimation); meshes and models (mesh generation, modeling, loads and boundary conditions, links between different modeling processes, resolution of linear systems, display of results etc..); vibration mechanics (modal and harmonic analysis, dynamics with shocks, direct transient dynamics, seismic analysis and aleatory dynamics, non-linear dynamics, dynamical sub-structuring); fluid-structure interactions (internal acoustics, mass, rigidity and damping); linear and non-linear thermal analysis; steels and metal industry (structure transformations); coupled problems (internal chaining, internal thermo-hydro-mechanical coupling, chaining with other codes); products and services. (J.S.)
Efficient quantum optical state engineering and applications
McCusker, Kevin T.
Over a century after the modern prediction of the existence of individual particles of light by Albert Einstein, a reliable source of this simple quantum state of one photon does not exist. While common light sources such as a light bulb, LED, or laser can produce a pulse of light with an average of one photon, there is (currently) no way of knowing the number of photons in that pulse without first absorbing (and thereby destroying) them. Spontaneous parametric down-conversion, a process in which one high-energy photon splits into two lower-energy photons, allows us to prepare a single-photon state by detecting one of the photons, which then heralds the existence of its twin. This process has been the workhorse of quantum optics, allowing demonstrations of a myriad of quantum processes and protocols, such as entanglement, cryptography, superdense coding, teleportation, and simple quantum computing demonstrations. All of these processes would benefit from better engineering of the underlying down-conversion process, but despite significant effort (both theoretical and experimental), optimization of this process is ongoing. The focus of this work is to optimize certain aspects of a down-conversion source, and then use this tool in novel experiments not otherwise feasible. Specifically, the goal is to optimize the heralding efficiency of the down-conversion photons, i.e., the probability that if one photon is detected, the other photon is also detected. This source is then applied to two experiments (a single-photon source, and a quantum cryptography implementation), and the detailed theory of an additional application (a source of Fock states and path-entangled states, called N00N states) is discussed, along with some other possible applications.
Robust dynamical decoupling for quantum computing and quantum memory.
Souza, Alexandre M; Alvarez, Gonzalo A; Suter, Dieter
2011-06-17
Dynamical decoupling (DD) is a popular technique for protecting qubits from the environment. However, unless special care is taken, experimental errors in the control pulses used in this technique can destroy the quantum information instead of preserving it. Here, we investigate techniques for making DD sequences robust against different types of experimental errors while retaining good decoupling efficiency in a fluctuating environment. We present experimental data from solid-state nuclear spin qubits and introduce a new DD sequence that is suitable for quantum computing and quantum memory.
Indian Academy of Sciences (India)
Network coding is a technique to increase the amount of information °ow in a network by mak- ing the key observation that information °ow is fundamentally different from commodity °ow. Whereas, under traditional methods of opera- tion of data networks, intermediate nodes are restricted to simply forwarding their incoming.
DEFF Research Database (Denmark)
Ejsing-Duun, Stine; Hansbøl, Mikala
Denne rapport rummer evaluering og dokumentation af Coding Class projektet1. Coding Class projektet blev igangsat i skoleåret 2016/2017 af IT-Branchen i samarbejde med en række medlemsvirksomheder, Københavns kommune, Vejle Kommune, Styrelsen for IT- og Læring (STIL) og den frivillige forening...... Coding Pirates2. Rapporten er forfattet af Docent i digitale læringsressourcer og forskningskoordinator for forsknings- og udviklingsmiljøet Digitalisering i Skolen (DiS), Mikala Hansbøl, fra Institut for Skole og Læring ved Professionshøjskolen Metropol; og Lektor i læringsteknologi, interaktionsdesign......, design tænkning og design-pædagogik, Stine Ejsing-Duun fra Forskningslab: It og Læringsdesign (ILD-LAB) ved Institut for kommunikation og psykologi, Aalborg Universitet i København. Vi har fulgt og gennemført evaluering og dokumentation af Coding Class projektet i perioden november 2016 til maj 2017...
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 15; Issue 7. Network Coding. K V Rashmi Nihar B Shah P Vijay Kumar. General Article Volume 15 Issue 7 July 2010 pp 604-621. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/015/07/0604-0621. Keywords.
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 10; Issue 1. Expander Codes - The Sipser–Spielman Construction. Priti Shankar. General Article Volume 10 ... Author Affiliations. Priti Shankar1. Department of Computer Science and Automation, Indian Institute of Science Bangalore 560 012, India.
Demonstration of blind quantum computing.
Barz, Stefanie; Kashefi, Elham; Broadbent, Anne; Fitzsimons, Joseph F; Zeilinger, Anton; Walther, Philip
2012-01-20
Quantum computers, besides offering substantial computational speedups, are also expected to preserve the privacy of a computation. We present an experimental demonstration of blind quantum computing in which the input, computation, and output all remain unknown to the computer. We exploit the conceptual framework of measurement-based quantum computation that enables a client to delegate a computation to a quantum server. Various blind delegated computations, including one- and two-qubit gates and the Deutsch and Grover quantum algorithms, are demonstrated. The client only needs to be able to prepare and transmit individual photonic qubits. Our demonstration is crucial for unconditionally secure quantum cloud computing and might become a key ingredient for real-life applications, especially when considering the challenges of making powerful quantum computers widely available.