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Sample records for quantum energy teleportation

  1. Towards Holographic Quantum Energy Teleportation

    CERN Document Server

    Giataganas, Dimitrios; Liu, Pei-Hua

    2016-01-01

    We propose a protocol of quantum energy teleportation (QET) for holographic conformal field theory (CFT) in 3-dimensional anti-de Sitter space with or without black hole. A generic QET protocol contains two steps: (i) Alice injects the energy into ground state by performing local measurement; (ii) the distant Bob extracts energy by performing local operation according to Alice's measurement outcome. In our holographic protocol, we mimic the step (i) by local projection of an interval of CFT ground state into an excited state described by Banados geometry. For the step (ii) we adopt the surface/state duality to evaluate the energy extraction by local deformation of UV surface as the holographic dual of Bob's local unitary operations. Our results show that this protocol always gains energy extraction. Moreover, the ratio of Bob's extraction energy density to the energy density of the excited state after Alice's local projection is a positive semi-definite and bounded function of the UV surface deformation profi...

  2. Quantum energy teleportation in a quantum Hall system

    Energy Technology Data Exchange (ETDEWEB)

    Yusa, Go; Izumida, Wataru; Hotta, Masahiro [Department of Physics, Tohoku University, Sendai 980-8578 (Japan)

    2011-09-15

    We propose an experimental method for a quantum protocol termed quantum energy teleportation (QET), which allows energy transportation to a remote location without physical carriers. Using a quantum Hall system as a realistic model, we discuss the physical significance of QET and estimate the order of energy gain using reasonable experimental parameters.

  3. Quantum Energy Teleportation with Trapped Ions

    CERN Document Server

    Hotta, Masahiro

    2009-01-01

    We analyze a protocol of quantum energy teleportation that transports energy from the left edge of a linear ion crystal to the right edge by local operations and classical communication at a speed much higher than the speed of the phonon in the crystal. A probe qubit is strongly coupled with the phonon fluctuation in the ground state during short time and is projectively measured in order to get information about this phonon fluctuation. During the measurement process, phonons are excited by the time-dependent measurement interaction and energy of the excited phonons must be infused from outside the system. The obtained information is announced to the right edge of the crystal through a classical channel. Even though the phonons excited at the left edge do not arrive at the right edge yet when the information arrives at the right edge, we are able to soon extract energy from the ion at the right edge by using the announced information. Because the intermediate ions of the crystal are not excited during the ex...

  4. Cascade quantum teleportation

    Institute of Scientific and Technical Information of China (English)

    ZHOU Nan-run; GONG Li-hua; LIU Ye

    2006-01-01

    In this letter a cascade quantum teleportation scheme is proposed. The proposed scheme needs less local quantum operations than those of quantum multi-teleportation. A quantum teleportation scheme based on entanglement swapping is presented and compared with the cascade quantum teleportation scheme. Those two schemes can effectively teleport quantum information and extend the distance of quantum communication.

  5. Quantum Energy Teleportation with a Linear Harmonic Chain

    CERN Document Server

    Nambu, Yasusada

    2010-01-01

    A protocol of quantum energy teleportation is proposed for a one-dimensional harmonic chain. A coherent-state POVM measurement is performed to coupled oscillators of the chain in the ground state accompanied by energy infusion to the system. This measurement consumes a part of ground state entanglement. Depending on the measurement result, a displacement operation is performed on a distant oscillator accompanied by energy extraction from the zero-point fluctuation of the oscillator. We find that the amount of consumed entanglement is bounded from below by a positive value that is proportional to the amount of teleported energy.

  6. Quantum Energy Teleportation with Electromagnetic Field: Discrete vs. Continuous Variables

    CERN Document Server

    Hotta, Masahiro

    2009-01-01

    Local measurements of quantum fluctuation in the vacuum state of electromagnetic field require energy infusion to the field. The infused energy is diffused to spatial infinity with light velocity and the state of the field soon becomes a local vacuum with zero energy around the measurement area. Of cource we cannot retrieve energy from this measurement area if we do not know the measurement result of the fluctuation. However, if the measurement result is available for us, we are able to extract energy from the local vacuum of the field, applying the protocol of quantum energy teleportation recently proposed. By performing a local unitary operation around the measurement area dependent on the measurement result, the fluctuaion of zero-point oscillation is squeezed and negative energy density appears around the area, accompanied by extraction of positive energy from the field. In this paper, we compare two different protocols of the energy retrieval. In the first protocol, a 1/2 spin is coupled with the fluctua...

  7. Quantum Entanglement and Teleportation

    OpenAIRE

    2011-01-01

    Even Einstein has to be wrong sometimes. However, when Einstein was wrong he created a 70 year debate about the strange behavior of quantum mechanics. His debate helped prove topics such as the indeterminacy of particle states, quantum entanglement, and a rather clever use of quantum entanglement known as quantum teleportation.

  8. Channel's Concurrence and Quantum Teleportation

    Institute of Scientific and Technical Information of China (English)

    LING Yin-Sheng

    2005-01-01

    Concurrence can measure the entanglement property of a system. If the channel is a pure state, positive concurrence state can afford the good performance in the teleportation process. If the channel ia a mixed state, positive concurrence state cannot assure the good performance in the teleportation. The conditions of the positive concurrence and the quantum teleportation in the Heisenberg spin ring is derived.

  9. Quantum communications: Teleportation becomes streetwise

    Science.gov (United States)

    Grosshans, Frédéric

    2016-10-01

    Quantum teleportation is at the heart of many quantum information protocols. Two teams have now performed it over several kilometres of metropolitan fibre networks, paving the way for future quantum technologies on the city scale.

  10. Quantum information. Teleportation - cryptography - quantum computer; Quanteninformation. Teleportation - Kryptografie - Quantencomputer

    Energy Technology Data Exchange (ETDEWEB)

    Koenneker, Carsten (comp.)

    2012-11-01

    The following topics are dealt with: Reality in the test facility, quantum teleportation, the reality of quanta, interaction-free quantum measurement, rules for quantum computers, quantum computers with ions, spintronics with diamond, the limits of the quantum computers, a view in the future of quantum optics. (HSI)

  11. Hybrid quantum teleportation: A theoretical model

    Energy Technology Data Exchange (ETDEWEB)

    Takeda, Shuntaro; Mizuta, Takahiro; Fuwa, Maria; Yoshikawa, Jun-ichi; Yonezawa, Hidehiro; Furusawa, Akira [Department of Applied Physics, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2014-12-04

    Hybrid quantum teleportation – continuous-variable teleportation of qubits – is a promising approach for deterministically teleporting photonic qubits. We propose how to implement it with current technology. Our theoretical model shows that faithful qubit transfer can be achieved for this teleportation by choosing an optimal gain for the teleporter’s classical channel.

  12. Quantum teleportation without classical channel

    Science.gov (United States)

    Al Amri, M.; Li, Zheng-Hong; Zubairy, M. Suhail

    2016-11-01

    For the first time, we show how quantum teleportation can be achieved without the assistance of classical channels. Our protocol does not need any pre-established entangled photon pairs beforehand. Just by utilizing quantum Zeno effect and couterfactual communication idea, we can achieve two goals; entangling a photon and an atom and also disentangling them by non-local interaction. Information is completely transferred from atom to photon with controllable disentanglement processes. More importantly, there is no need to confirm teleportation results via classical channels.

  13. Quantum teleportation of entangled squeezed vacuum states

    Institute of Scientific and Technical Information of China (English)

    蔡新华

    2003-01-01

    An optical scheme for probabilistic teleporting entangled squeezed vacuum states (SVS) is proposed. In this scheme,the teleported state is a bipartite entangled SVS,and the quantum channel is a tripartite entangled SVS.The process of the teleportation is achieved by using a 50/50 symmetric beamsplitter and photon detectors with the help of classical information.

  14. Quantum teleportation between moving detectors

    CERN Document Server

    Lin, Shih-Yuin; Hu, B L

    2015-01-01

    It is commonly believed that the fidelity of quantum teleportation using localized quantum objects with one party or both accelerated in vacuum would be degraded due to the heat-up by the Unruh effect. In this paper we point out that the Unruh effect is not the whole story in accounting for all the relativistic effects in quantum teleportation. First, there could be degradation of fidelity by a common field environment even when both quantum objects are in inertial motion. Second, relativistic effects entering the description of the dynamics such as frame dependence, time dilation, and Doppler shift, already existent in inertial motion, can compete with or even overwhelm the effect due to uniform acceleration in a quantum field. We show it is not true that larger acceleration of an object would necessarily lead to a faster degradation of fidelity. These claims are based on four cases of quantum teleportation we studied using two Unruh-DeWitt detectors coupled via a common quantum field initially in the Minkow...

  15. Quantum teleportation with continuous measurements

    Science.gov (United States)

    Greplova, Eliska; Mølmer, Klaus; Andersen, Christian Kraglund

    2016-10-01

    We propose a scheme for quantum teleportation between two qubits, coupled sequentially to a cavity field. An implementation of the scheme is analyzed with superconducting qubits and a transmission line resonator, where measurements are restricted to continuous probing of the field leaking from the resonator rather than instantaneous projective Bell state measurement. We show that the past quantum state formalism S. Gammelmark, B. Julsgaard, and K. Mølmer, Phys. Rev. Lett. 111, 160401 (2013), 10.1103/PhysRevLett.111.160401 can be successfully applied to estimate what would have been the most likely Bell measurement outcome conditioned on our continuous signal record. This information determines which local operation on the target qubit yields the optimal teleportation fidelity. Our results emphasize the significance of applying a detailed analysis of quantum measurements in feedforward protocols in nonideal leaky quantum systems.

  16. Optimal continuous-variable teleportation under energy constraint

    Science.gov (United States)

    Lee, Jaehak; Park, Jiyong; Nha, Hyunchul

    2017-05-01

    Quantum teleportation is one of the crucial protocols in quantum information processing. It is important to accomplish an efficient teleportation under practical conditions, aiming at a higher fidelity desirably using fewer resources. The continuous-variable (CV) version of quantum teleportation was first proposed using a Gaussian state as a quantum resource, while other attempts were also made to improve performance by applying non-Gaussian operations. We investigate the CV teleportation to find its ultimate fidelity under energy constraint identifying an optimal quantum state. For this purpose, we present a formalism to evaluate teleportation fidelity as an expectation value of an operator. Using this formalism, we prove that the optimal state must be a form of photon-number entangled states. We further show that Gaussian states are near optimal, while non-Gaussian states make a slight improvement and therefore are rigorously optimal, particularly in the low-energy regime.

  17. Quantum teleportation criteria for continuous variables

    CERN Document Server

    Grangier, P; Grangier, Philippe; Grosshans, Frederic

    2000-01-01

    We discuss the criteria presently used for evaluating the efficiency of quantum teleportation schemes for continuous variables. It is argued that the fidelity criterion used so far has some severe drawbacks, and that a fidelity value larger than 2/3 is actually required for successful quantum teleportation. This value has never been reached experimentally so far.

  18. Quantum teleportation of propagating quantum microwaves

    Energy Technology Data Exchange (ETDEWEB)

    Di Candia, R.; Felicetti, S.; Sanz, M. [University of the Basque Country UPV/EHU, Department of Physical Chemistry, Bilbao (Spain); Fedorov, K.G.; Menzel, E.P. [Bayerische Akademie der Wissenschaften, Walther-Meissner-Institut, Garching (Germany); Technische Universitaet Muenchen, Physik-Department, Garching (Germany); Zhong, L.; Deppe, F.; Gross, R. [Bayerische Akademie der Wissenschaften, Walther-Meissner-Institut, Garching (Germany); Technische Universitaet Muenchen, Physik-Department, Garching (Germany); Nanosystems Initiative Munich (NIM), Muenchen (Germany); Marx, A. [Bayerische Akademie der Wissenschaften, Walther-Meissner-Institut, Garching (Germany); Solano, E. [University of the Basque Country UPV/EHU, Department of Physical Chemistry, Bilbao (Spain); Basque Foundation for Science, IKERBASQUE, Bilbao (Spain)

    2015-12-15

    Propagating quantum microwaves have been proposed and successfully implemented to generate entanglement, thereby establishing a promising platform for the realisation of a quantum communication channel. However, the implementation of quantum teleportation with photons in the microwave regime is still absent. At the same time, recent developments in the field show that this key protocol could be feasible with current technology, which would pave the way to boost the field of microwave quantum communication. Here, we discuss the feasibility of a possible implementation of microwave quantum teleportation in a realistic scenario with losses. Furthermore, we propose how to implement quantum repeaters in the microwave regime without using photodetection, a key prerequisite to achieve long distance entanglement distribution. (orig.)

  19. Teleportation of Two Quantum States via the Quantum Computation

    Institute of Scientific and Technical Information of China (English)

    FENG Mang; ZHU Xi-Wen; FANG Xi-Ming; YAN Min; SHI Lei

    2000-01-01

    A scheme of teleportation of two unknown quantum states via quantum computation is proposed. The comparison with the former proposals shows that our scheme is more in tune with the original teleportation proposal and the effciency is higher. The teleportation of an unknown entangled state is also discussed.

  20. A noise immunity controlled quantum teleportation protocol

    Science.gov (United States)

    Li, Dong-fen; Wang, Rui-jin; Zhang, Feng-li; Baagyere, Edward; Qin, Zhen; Xiong, Hu; Zhan, Huayi

    2016-08-01

    With the advent of the Internet and information and communication technology, quantum teleportation has become an important field in information security and its application areas. This is because quantum teleportation has the ability to attain a timely secret information delivery and offers unconditional security. And as such, the field of quantum teleportation has become a hot research topic in recent years. However, noise has serious effect on the safety of quantum teleportation within the aspects of information fidelity, channel capacity and information transfer. Therefore, the main purpose of this paper is to address these problems of quantum teleportation. Firstly, in order to resist collective noise, we construct a decoherence-free subspace under different noise scenarios to establish a two-dimensional fidelity quantum teleportation models. And also create quantum teleportation of multiple degree of freedom, and these models ensure the accuracy and availability of the exchange of information and in multiple degree of freedom. Secondly, for easy preparation, measurement and implementation, we use super dense coding features to build an entangled quantum secret exchange channel. To improve the channel utilization and capacity, an efficient super dense coding method based on ultra-entanglement exchange is used. Thirdly, continuous variables of the controlled quantum key distribution were designed for quantum teleportation; in addition, we perform Bell-basis measurement under the collective noise and also prepare the storage technology of quantum states to achieve one-bit key by three-photon encoding to improve its security and efficiency. We use these two methods because they conceal information, resist a third party attack and can detect eavesdropping. Our proposed methods, according to the security analysis, are able to solve the problems associated with the quantum teleportation under various noise environments.

  1. A noise immunity controlled quantum teleportation protocol

    Science.gov (United States)

    Li, Dong-fen; Wang, Rui-jin; Zhang, Feng-li; Baagyere, Edward; Qin, Zhen; Xiong, Hu; Zhan, Huayi

    2016-11-01

    With the advent of the Internet and information and communication technology, quantum teleportation has become an important field in information security and its application areas. This is because quantum teleportation has the ability to attain a timely secret information delivery and offers unconditional security. And as such, the field of quantum teleportation has become a hot research topic in recent years. However, noise has serious effect on the safety of quantum teleportation within the aspects of information fidelity, channel capacity and information transfer. Therefore, the main purpose of this paper is to address these problems of quantum teleportation. Firstly, in order to resist collective noise, we construct a decoherence-free subspace under different noise scenarios to establish a two-dimensional fidelity quantum teleportation models. And also create quantum teleportation of multiple degree of freedom, and these models ensure the accuracy and availability of the exchange of information and in multiple degree of freedom. Secondly, for easy preparation, measurement and implementation, we use super dense coding features to build an entangled quantum secret exchange channel. To improve the channel utilization and capacity, an efficient super dense coding method based on ultra-entanglement exchange is used. Thirdly, continuous variables of the controlled quantum key distribution were designed for quantum teleportation; in addition, we perform Bell-basis measurement under the collective noise and also prepare the storage technology of quantum states to achieve one-bit key by three-photon encoding to improve its security and efficiency. We use these two methods because they conceal information, resist a third party attack and can detect eavesdropping. Our proposed methods, according to the security analysis, are able to solve the problems associated with the quantum teleportation under various noise environments.

  2. Evaluating quantum teleportation of coherent states

    CERN Document Server

    Grangier, P

    2000-01-01

    By using an argument based upon EPR non-separability of the entanglement resource, it was recently argued that a fidelity value larger than 2/3 is required for successful quantum teleportation of coherent states (arXiv:quant-ph/0009079). Here we recover this same conclusion from simple considerations about information exchange during the teleportation process.

  3. Quantum logic networks for probabilistic teleportation

    Institute of Scientific and Technical Information of China (English)

    刘金明; 张永生; 郭光灿

    2003-01-01

    By means of the primitive operations consisting of single-qubit gates, two-qubit controlled-not gates, Von Neuman measurement and classically controlled operations, we construct efficient quantum logic networks for implementing probabilistic teleportation of a single qubit, atwo-particle entangled state, and an N-particle entanglement. Based on the quantum networks, we show that after the partially entangled states are concentrated into maximal entanglement,the above three kinds of probabilistic teleportation are the same as the standard teleportation using the corresponding maximally entangled states as the quantum channels.

  4. Quantum logic networks for probabilistic teleportation

    Institute of Scientific and Technical Information of China (English)

    刘金明; 张永生; 等

    2003-01-01

    By eans of the primitive operations consisting of single-qubit gates.two-qubit controlled-not gates,Von Neuman measurement and classically controlled operations.,we construct efficient quantum logic networks for implementing probabilistic teleportation of a single qubit,a two-particle entangled state,and an N-particle entanglement.Based on the quantum networks,we show that after the partially entangled states are concentrated into maximal entanglement,the above three kinds of probabilistic teleportation are the same as the standard teleportation using the corresponding maximally entangled states as the quantum channels.

  5. Teleportation of Quantum States through Mixed Entangled Pairs

    Institute of Scientific and Technical Information of China (English)

    ZHENG Shi-Biao

    2006-01-01

    @@ We describe a protocol for quantum state teleportation via mixed entangled pairs. With the help of an ancilla,near-perfect teleportation might be achieved. For pure entangled pairs, perfect teleportation might be achieved with a certain probability without using an ancilla. The protocol is generalized to teleportation of multiparticle states and quantum secret sharing.

  6. Unitary Transformation in Quantum Teleportation

    Institute of Scientific and Technical Information of China (English)

    WANG Zheng-Chuan

    2006-01-01

    In the well-known treatment of quantum teleportation, the receiver should convert the state of his EPR particle into the replica of the unknown quantum state by one of four possible unitary transformations. However, the importance of these unitary transformations must be emphasized. We will show in this paper that the receiver cannot transform the state of his particle into an exact replica of the unknown state which the sender wants to transfer if he has not a proper implementation of these unitary transformations. In the procedure of converting state, the inevitable coupling between EPR particle and environment which is needed by the implementation of unitary transformations will reduce the accuracy of the replica.

  7. Multiplexed CV quantum teleportation for high rates in quantum communication

    CERN Document Server

    Christ, Andreas; Silberhorn, Christine

    2012-01-01

    A major challenge of today's quantum communication systems lies in the transmission of quantum information with high rates over long distances in the presence of unavoidable losses. Thereby the achievable quantum communication rate is fundamentally limited by the amount of energy that can be transmitted per use of the channel. It is hence vital to develop quantum communication protocols which encode quantum information as energy efficiently as possible. To this aim we investigate continuous-variable quantum teleportation as a method of distributing quantum information. We explore the possibility to encode information on multiple optical modes and derive upper and lower bounds on the achievable quantum channel capacities. This analysis enables us to benchmark single-mode vs. multi-mode entanglement resources. Our research reveals that multiplexing does not only feature an enhanced energy efficiency, significantly increasing the achievable quantum communication rates in comparison to single-mode coding, but als...

  8. Quantum teleportation over the Swisscom telecommunication network

    CERN Document Server

    Landry, O; Beveratos, A; Zbinden, H; Gisin, Nicolas; Landry, Olivier; Beveratos, Alexios; Zbinden, Hugo; Gisin, Nicolas

    2006-01-01

    We present a quantum teleportation experiment in the quantum relay configuration using the installed telecommunication network of Swisscom. In this experiment, the Bell state measurement occurs well after the entanglement has been distributed, at a point where the photon upon which data is teleported is already far away, and the entangled qubits are photons created from a different crystal and laser pulse than the teleported qubit. A raw fidelity of 0.93+/-0.04 has been achieved using a heralded single-photon source.

  9. Teleportation in an indivisible quantum system

    Directory of Open Access Journals (Sweden)

    Kiktenko E.O.

    2016-01-01

    Full Text Available Teleportation protocol is conventionally treated as a method for quantum state transfer between two spatially separated physical carriers. Recent experimental progress in manipulation with high-dimensional quantum systems opens a new framework for implementation of teleportation protocols. We show that the one-qubit teleportation can be considered as a state transfer between subspaces of the whole Hilbert space of an indivisible eight-dimensional system. We explicitly show all corresponding operations and discuss an alternative way of implementation of similar tasks.

  10. Ground-to-satellite quantum teleportation.

    Science.gov (United States)

    Ren, Ji-Gang; Xu, Ping; Yong, Hai-Lin; Zhang, Liang; Liao, Sheng-Kai; Yin, Juan; Liu, Wei-Yue; Cai, Wen-Qi; Yang, Meng; Li, Li; Yang, Kui-Xing; Han, Xuan; Yao, Yong-Qiang; Li, Ji; Wu, Hai-Yan; Wan, Song; Liu, Lei; Liu, Ding-Quan; Kuang, Yao-Wu; He, Zhi-Ping; Shang, Peng; Guo, Cheng; Zheng, Ru-Hua; Tian, Kai; Zhu, Zhen-Cai; Liu, Nai-Le; Lu, Chao-Yang; Shu, Rong; Chen, Yu-Ao; Peng, Cheng-Zhi; Wang, Jian-Yu; Pan, Jian-Wei

    2017-09-07

    An arbitrary unknown quantum state cannot be measured precisely or replicated perfectly. However, quantum teleportation enables unknown quantum states to be transferred reliably from one object to another over long distances, without physical travelling of the object itself. Long-distance teleportation is a fundamental element of protocols such as large-scale quantum networks and distributed quantum computation. But the distances over which transmission was achieved in previous teleportation experiments, which used optical fibres and terrestrial free-space channels, were limited to about 100 kilometres, owing to the photon loss of these channels. To realize a global-scale 'quantum internet' the range of quantum teleportation needs to be greatly extended. A promising way of doing so involves using satellite platforms and space-based links, which can connect two remote points on Earth with greatly reduced channel loss because most of the propagation path of the photons is in empty space. Here we report quantum teleportation of independent single-photon qubits from a ground observatory to a low-Earth-orbit satellite, through an uplink channel, over distances of up to 1,400 kilometres. To optimize the efficiency of the link and to counter the atmospheric turbulence in the uplink, we use a compact ultra-bright source of entangled photons, a narrow beam divergence and high-bandwidth and high-accuracy acquiring, pointing and tracking. We demonstrate successful quantum teleportation of six input states in mutually unbiased bases with an average fidelity of 0.80 ± 0.01, well above the optimal state-estimation fidelity on a single copy of a qubit (the classical limit). Our demonstration of a ground-to-satellite uplink for reliable and ultra-long-distance quantum teleportation is an essential step towards a global-scale quantum internet.

  11. Optimal conclusive teleportation of quantum states

    CERN Document Server

    Roa, L; Fuentes-Guridi, I

    2003-01-01

    Quantum teleportation of qudits is revisited. In particular, we analyze the case where the quantum channel corresponds to a non-maximally entangled state and show that the success of the protocol is directly related to the problem of distinguishing non-orthogonal quantum states. The teleportation channel can be seen as a coherent superposition of two channels, one of them being a maximally entangled state thus, leading to perfect teleportation and the other, corresponding to a non-maximally entangled state living in a subspace of the d-dimensional Hilbert space. The second channel leads to a teleported state with reduced fidelity. We calculate the average fidelity of the process and show its optimality.

  12. Canonical Quantum Teleportation of Two-Particle Arbitrary State

    Institute of Scientific and Technical Information of China (English)

    HAO Xiang; ZHU Shi-Qun

    2005-01-01

    The canonical quantum teleportation of two-particle arbitrary state is realized by means of phase operator and number operator. The maximally entangled eigenstates between the difference of phase operators and the sum of number operators are considered as the quantum channels. In contrast to the standard quantum teleportation, the different unitary local operation of canonical teleportation can be simplified by a general expression.

  13. Quantum remote control Teleportation of unitary operations

    CERN Document Server

    Huelga, S F; Chefles, A; Plenio, M B

    2001-01-01

    We consider the implementation of an unknown arbitrary unitary operation U upon a distant quantum system. This teleportation of U can be viewed as a quantum remote control. We investigate the protocols which achieve this using local operations, classical communication and shared entanglement (LOCCSE). Lower bounds on the necessary entanglement and classical communication are determined using causality and the linearity of quantum mechanics. We examine in particular detail the resources required if the remote control is to be implemented as a classical black box. Under these circumstances, we prove that the required resources are, necessarily, those needed for implementation by bidirectional state teleportation.

  14. Quantum entanglement and teleportation using statistical correlations

    Indian Academy of Sciences (India)

    Atul Kumar; Mangala Sunder Krishnan

    2009-09-01

    A study of quantum teleportation using two and three-particle correlated density matrix is presented. A criterion based on standard quantum statistical correlations employed in the many-body virial expansion is used to determine the extent of entanglement for a 2-particle system. A relation between the probability and statistical parameters is established using the correlated density matrices for the particles.

  15. Teleportation of the Relativistic Quantum Field

    CERN Document Server

    Laiho, R; Nazin, S S

    2000-01-01

    The process of teleportation of a completely unknown one-particle state of a free relativistic quantum field is considered. In contrast to the non-relativistic quantum mechanics, the teleportation of an unknown state of the quantum field cannot be in principle described in terms of a measurement in a tensor product of two Hilbert spaces to which the unknown state and the state of the EPR-pair belong. The reason is of the existence of a cyclic (vacuum) state common to both the unknown state and the EPR-pair. Due to the common vacuum vector and the microcausality principle (commutation relations for the field operators), the teleportation amplitude contains inevitably contributions which are irrelevant to the teleportation process. Hence in the relativistic theory the teleportation in the sense it is understood in the non-relativistic quantum mechanics proves to be impossible because of the impossibility of the realization of the appropriate measurement as a tensor product of the measurements related to the ind...

  16. Controlled quantum teleportation and secure direct communication

    Institute of Scientific and Technical Information of China (English)

    Gao Ting; Yan Feng-Li; Wang Zhi-Xi

    2005-01-01

    We present a controlled quantum teleportation protocol. In the protocol, quantum information of an unknown state of a 2-level particle is faithfully transmitted from a sender Alice to a remote receiver Bob via an initially shared triplet of entangled particles under the control of the supervisor Charlie. The distributed entangled particles shared by Alice, Bob and Charlie function as a quantum information channel for faithful transmission. We also propose a controlled and secure direct communication scheme by means of this teleportation. After ensuring the security of the quantum channel, Alice encodes the secret message directly on a sequence of particle states and transmits them to Bob supervised by Charlie using this controlled quantum teleportation. Bob can read out the encoded message directly by the measurement on his qubit. In this scheme, the controlled quantum teleportation transmits Alice's message without revealing any information to a potential eavesdropper. Because there is not a transmission of the qubit carrying the secret message between Alice and Bob in the public channel, it is completely secure for controlled and direct secret communication if perfect quantum channel is used. The special feature of this scheme is that the communication between two sides depends on the agreement of a third side to co-operate.

  17. Teleportations of Mixed States and Multipartite Quantum States

    Institute of Scientific and Technical Information of China (English)

    YU Chang-Shui; WANG Ya-Hong; SONG He-Shan

    2007-01-01

    In this paper, we propose a protocol to deterministically teleport an unknown mixed state of qubit by utilizing a maximally bipartite entangled state of qubits as quantum channel. Ifa non-maximally entangled bipartite pure state is employed as quantum channel, the unknown mixed quantum state of qubit can be teleported with 1 - √1 - C2 probability, where C is the concurrence of the quantum channel. The protocol can also be generalized to teleport a mixed state of qudit or a multipartite mixed state. More important purpose is that, on the basis of the protocol, the teleportation of an arbitrary multipartite (pure or mixed) quantum state can be decomposed into the teleportation of each subsystem by employing separate entangled states as quantum channels. In the case of deterministic teleportation,Bob only needs to perform unitary transformations on his single particles in order to recover the initial teleported multipartite quantum state.

  18. Tight Reference Frame–Independent Quantum Teleportation

    Directory of Open Access Journals (Sweden)

    Dominic Verdon

    2017-01-01

    Full Text Available We give a tight scheme for teleporting a quantum state between two parties whose reference frames are misaligned by an action of a finite symmetry group. Unlike previously proposed schemes, ours requires no additional tokens or data to be passed between the participants; the same amount of classical information is transferred as for ordinary quantum teleportation, and the Hilbert space of the entangled resource is of the same size. In the terminology of Peres and Scudo, our protocol relies on classical communication of unspeakable information.

  19. Quantum Teleportation circuit using Matlab and Mathematica

    Directory of Open Access Journals (Sweden)

    Ms.Swati Sharma,

    2010-08-01

    Full Text Available This Paper describes a basic Quantum Teleportation circuit using mat lab Qlib tool. Teleportation is a new and exciting field of future communication. We know that security in data communication is a major concern nowadays. Among the encryption technologies that are available at present, shared key is the most reliable which depends on secure key generation and distribution. Teleportation/ ntanglement is a perfect solution for secure key generation and distribution, as for the no cloning theorem of quantum mechanics any attempt to intercept the key by the eavesdropper will be detectable immediately. A program is simulated with successful simulation which give successful transfer of random qubit to output and which governs perfect communication between Alice and Bob.

  20. Quantum teleportation between remote atomic-ensemble quantum memories

    CERN Document Server

    Bao, Xiao-Hui; Li, Che-Ming; Yuan, Zhen-Sheng; Lu, Chao-Yang; Pan, Jian-Wei

    2012-01-01

    Quantum teleportation and quantum memory are two crucial elements for large-scale quantum networks. With the help of prior distributed entanglement as a "quantum channel", quantum teleportation provides an intriguing means to faithfully transfer quantum states among distant locations without actual transmission of the physical carriers. Quantum memory enables controlled storage and retrieval of fast-flying photonic quantum bits with stationary matter systems, which is essential to achieve the scalability required for large-scale quantum networks. Combining these two capabilities, here we realize quantum teleportation between two remote atomic-ensemble quantum memory nodes, each composed of 100 million rubidium atoms and connected by a 150-meter optical fiber. The spinwave state of one atomic ensemble is mapped to a propagating photon, and subjected to Bell-state measurements with another single photon that is entangled with the spinwave state of the other ensemble. Two-photon detection events herald the succe...

  1. Quantum teleportation across a metropolitan fibre network

    Science.gov (United States)

    Valivarthi, Raju; Puigibert, Marcel. Li Grimau; Zhou, Qiang; Aguilar, Gabriel H.; Verma, Varun B.; Marsili, Francesco; Shaw, Matthew D.; Nam, Sae Woo; Oblak, Daniel; Tittel, Wolfgang

    2016-10-01

    If a photon interacts with a member of an entangled photon pair via a Bell-state measurement (BSM), its state is teleported over principally arbitrary distances onto the pair's second member. Since 1997, this puzzling prediction of quantum mechanics has been demonstrated many times. However, with two exceptions, only the photon that received the teleported state, if any, travelled far, while the photons partaking in the BSM were always measured close to where they were created. Here, using the Calgary fibre network, we report quantum teleportation from a telecom photon at 1,532 nm wavelength, interacting with another telecom photon after both have travelled several kilometres and over a combined beeline distance of 8.2 km, onto a photon at 795 nm wavelength. This improves the distance over which teleportation takes place to 6.2 km. Our demonstration establishes an important requirement for quantum repeater-based communications and constitutes a milestone towards a global quantum internet.

  2. Relativistic Quantum Teleportation with superconducting circuits

    CERN Document Server

    Friis, Nicolai; Truong, Kevin; Sabín, Carlos; Solano, Enrique; Johansson, Göran; Fuentes, Ivette

    2012-01-01

    We study the effects of relativistic motion on quantum teleportation and propose a realizable experiment where our results can be tested. We compute bounds on the optimal fidelity of teleportation when one of the observers undergoes non-uniform motion for a finite time. The upper bound to the optimal fidelity is degraded due to the observer's motion however, we discuss how this degradation can be corrected. These effects are observable for experimental parameters that are within reach of cutting-edge superconducting technology.

  3. Quantum teleportation between moving detectors in a quantum field

    CERN Document Server

    Lin, Shih-Yuin; Chou, Chung-Hsien; Hu, B L

    2012-01-01

    We consider the quantum teleportation of continuous variables modeled by Unruh-DeWitt detectors coupled to a common quantum field initially in the Minkowski vacuum. An unknown coherent state of an Unruh-DeWitt detector is teleported from one inertial agent (Alice) to an almost uniformly accelerated agent (Rob, for relativistic motion), using a detector pair initially entangled and shared by these two agents. The averaged physical fidelity of quantum teleportation, which is independent of the observer's frame, always drops below the best fidelity value from classical teleportation before the detector pair becomes disentangled with the measure of entanglement evaluated around the future lightcone of the joint measurement event by Alice. The distortion of the quantum state of the entangled detector pair from the initial state can suppress the fidelity significantly even when the detectors are still strongly entangled around the lightcone. We point out that the dynamics of entanglement of the detector pair observ...

  4. Quantum teleportation of nonclassical wave packets: An effective multimode theory

    Energy Technology Data Exchange (ETDEWEB)

    Benichi, Hugo; Takeda, Shuntaro; Lee, Noriyuki; Furusawa, Akira [Department of Applied Physics, University of Tokyo, Tokyo (Japan)

    2011-07-15

    We develop a simple and efficient theoretical model to understand the quantum properties of broadband continuous variable quantum teleportation. We show that, if stated properly, the problem of multimode teleportation can be simplified to teleportation of a single effective mode that describes the input state temporal characteristic. Using that model, we show how the finite bandwidth of squeezing and external noise in the classical channel affect the output teleported quantum field. We choose an approach that is especially relevant for the case of non-Gaussian nonclassical quantum states and we finally back-test our model with recent experimental results.

  5. Entanglement fidelity of the standard quantum teleportation channel

    Energy Technology Data Exchange (ETDEWEB)

    Li, Gang; Ye, Ming-Yong, E-mail: myye@fjnu.edu.cn; Lin, Xiu-Min

    2013-09-16

    We consider the standard quantum teleportation protocol where a general bipartite state is used as entanglement resource. We use the entanglement fidelity to describe how well the standard quantum teleportation channel transmits quantum entanglement and give a simple expression for the entanglement fidelity when it is averaged on all input states.

  6. Asymptotic teleportation scheme as a universal programmable quantum processor.

    Science.gov (United States)

    Ishizaka, Satoshi; Hiroshima, Tohya

    2008-12-12

    We consider a scheme of quantum teleportation where a receiver has multiple (N) output ports and obtains the teleported state by merely selecting one of the N ports according to the outcome of the sender's measurement. We demonstrate that such teleportation is possible by showing an explicit protocol where N pairs of maximally entangled qubits are employed. The optimal measurement performed by a sender is the square-root measurement, and a perfect teleportation fidelity is asymptotically achieved for a large N limit. Such asymptotic teleportation can be utilized as a universal programmable processor.

  7. Unidirectional Quantum Remote Control:Teleportation of Control-State

    Institute of Scientific and Technical Information of China (English)

    ZHENG Yi-Zhuang; GU Yong-Jian; WU Gui-Chu; GUO Guang-Can

    2003-01-01

    We investigate the problem of teleportation of unitary operations by unidirectional control-state telepor-tation and propose a scheme called unidirectional quantum remote control. The scheme is based on the isomorphismbetween operation and state. It allows us to store a unitary operation in a control state, thereby teleportation of theunitary operation can be implemented by unidirectional teleportation of the control-state. We find that the probabilityof success for implementing an arbitrary unitary operation on arbitrary M-qubit state by unidirectional control-stateteleportation is 4-M, and 2M ebits and 4M cbits are consumed in each teleportation.

  8. Continuous-variable quantum teleportation in bosonic structured environments

    Energy Technology Data Exchange (ETDEWEB)

    He Guangqiang; Zhang Jingtao; Zhu Jun; Zeng Guihua [State Key Laboratory of Advanced Optical Communication Systems and Networks, Department of Electronic Engineering, Shanghai Jiaotong University, Shanghai 200240 (China)

    2011-09-15

    The effects of dynamics of continuous-variable entanglement under the various kinds of environments on quantum teleportation are quantitatively investigated. Only under assumption of the weak system-reservoir interaction, the evolution of teleportation fidelity is analytically derived and is numerically plotted in terms of environment parameters including reservoir temperature and its spectral density, without Markovian and rotating wave approximations. We find that the fidelity of teleportation is a monotonically decreasing function for Markovian interaction in Ohmic-like environments, while it oscillates for non-Markovian ones. According to the dynamical laws of teleportation, teleportation with better performances can be implemented by selecting the appropriate time.

  9. Information flow in quantum teleportation

    Indian Academy of Sciences (India)

    Andrew Whitaker

    2002-08-01

    The flow of information is discussed in the context of quantum teleportation. Situations are described which use a sequence of systems of particles in which, though there is no claim of faster-than-light signaling, it is plausible to suggest that information about measurement procedures in one wing of the apparatus does reach the other end in a non-local manner. The definition of the term ’parameter dependence’ is discussed.

  10. Multi-state Quantum Teleportation via One Entanglement State

    Institute of Scientific and Technical Information of China (English)

    GUO Ying; ZENG Gui-Hua; Moon Ho Lee

    2008-01-01

    A multi-sender-controlled quantum teleportation scheme is proposed to teleport several secret quan-tum states from different senders to a distance receiver based on only one Einstein-Podolsky-Rosen (EPR) pair with controlled-NOT (CNOT) gates. In the present scheme, several secret single-qubit quantum states are encoded into a multi-qubit entangled quantum state. Two communication modes, i.e., the detecting mode and the message mode, are employed so that the eavesdropping can be detected easily and the teleported message may be recovered efficiently. It has an advantage over teleporting several different quantum states for one scheme run with more efficiency than the previous quantum teleportation schemes.

  11. An Overview of Quantum Teleportation for the Intelligence Community

    Energy Technology Data Exchange (ETDEWEB)

    Humble, Travis S [ORNL

    2007-01-01

    Quantum teleportation is a communication protocol for the exchange of information between remotely separated parties. We survey some prominent applications of quantum teleportation that show potential for collecting and analyzing intelligence. In addition to a background review of the underlying principles, we highlight the use of quantum teleportation in quantum key distribution, long-distance quantum communication networks, and quantum computing. The latter applications are significant for the Intelligence Community as they show promise for cracking conventional public-key encryption systems and providing alternate key distribution systems that are secure against attack.

  12. Quantum state transfer between light and matter via teleportation

    DEFF Research Database (Denmark)

    Krauter, Hanna; Sherson, Jacob; Polzik, Eugene Simon

    2010-01-01

    Quantum teleportation is an interesting feature of quantum mechanics. Entanglement is used as a link between two remote locations to transfer a quantum state without physically sending it - a process that cannot be realized utilizing merely classical tools. Furthermore it has become evident...... that teleportation is also an important element of future quantum networks and it can be an ingredient for quantum computation. This article reports for the first time the teleportation from light to atoms. In the experiment discussed, the quantum state of a light beam is transferred to an atomic ensemble. The key...

  13. Quantum Teleportation of a Three-Particle Entangled State

    Institute of Scientific and Technical Information of China (English)

    刘金明; 郭光灿

    2002-01-01

    We present a scheme for teleporting a three-particle entangled state to three remote particles. In this scheme, three pairs of pure nonmaximally entangled states are considered as quantum channels. It is found that by means of optimal discrimination between two nonorthogonal quantum states, probabilistic teleportation of the three-particle entangled state can be achieved.

  14. Quantum teleportation of one- and two-photon superposition states

    Institute of Scientific and Technical Information of China (English)

    李英; 张天才; 张俊香; 谢常德

    2003-01-01

    Quantum teleportation of one- and two-photon superposition states based on EPR entanglement of continuouswave two-mode squeezed state is discussed. The fidelities of teleportation are deduced for two different input quantum states. The dependence of the fidelity on the parameters of EPR entanglement and the gain of the classical channels are shown numerically. Comparing with the teleportation of Fock state and coherent state, it is pointed out that for given EPR entanglement and classical gain, the higher the nonclassicality of the input state, the lower the accessible fidelity of teleportation.

  15. Unidirectional Quantum Remote Control: Teleportation of Control-State

    Institute of Scientific and Technical Information of China (English)

    ZHENGYi-Zhuang; GUYong-Jian; WUGui-Chu; GUOGuang-Can

    2003-01-01

    We investigate the problem of teleportation of unitary operations by unidirectional control-state telepor-ration and propose a scheme called unidirectional quantum remote control. The scheme is based on the isomorphism between operation and state. It allows us to store a unitary operation in a control state, thereby teleportatSon of the unitary operation can be implemented by unidirectional teleportation of the control-state. We find that the probability of success for implementing an arbitrary unitary operation on arbitrary A~-qubit state by unidirectional control-state teleportation is 4-M, and 2M ebits and 4M cbits are consumed in each teleportation.

  16. Continuous-variable quantum identity authentication based on quantum teleportation

    Science.gov (United States)

    Ma, Hongxin; Huang, Peng; Bao, Wansu; Zeng, Guihua

    2016-06-01

    A continuous-variable quantum identity authentication protocol, which is based on quantum teleportation, is presented by employing two-mode squeezed vacuum state and coherent state. The proposed protocol can verify user's identity efficiently with a new defined fidelity parameter. Update of authentication key can also be implemented in our protocol. Moreover, the analysis shows its feasibility and security under the general Gaussian-cloner attack on authentication key, which is guaranteed by quantum entanglement, insertion of decoy state and random displacement.

  17. Quantum Teleportation of Tripartite Arbitrary State via W State

    Institute of Scientific and Technical Information of China (English)

    XUE Zheng-Yuan; YI You-Min; CAO Zhuo-Liang

    2005-01-01

    A scheme of teleportation of a tripartite state via W state is suggested. The W state serves as quantum channels. Standard Bell-state measurements and Von Neumann measurements are performed. After the sender operates the measurements and informs the receiver her results, he can reconstruct the original state by the corresponding unitary transformation. The probability of the successful teleportation is also obtained.

  18. Quantum teleportation and Birman-Murakami-Wenzl algebra

    Science.gov (United States)

    Zhang, Kun; Zhang, Yong

    2017-02-01

    In this paper, we investigate the relationship of quantum teleportation in quantum information science and the Birman-Murakami-Wenzl (BMW) algebra in low-dimensional topology. For simplicity, we focus on the two spin-1/2 representation of the BMW algebra, which is generated by both the Temperley-Lieb projector and the Yang-Baxter gate. We describe quantum teleportation using the Temperley-Lieb projector and the Yang-Baxter gate, respectively, and study teleportation-based quantum computation using the Yang-Baxter gate. On the other hand, we exploit the extended Temperley-Lieb diagrammatical approach to clearly show that the tangle relations of the BMW algebra have a natural interpretation of quantum teleportation. Inspired by this interpretation, we construct a general representation of the tangle relations of the BMW algebra and obtain interesting representations of the BMW algebra. Therefore, our research sheds a light on a link between quantum information science and low-dimensional topology.

  19. Probabilistic Teleportation via Quantum Channel with Partial Information

    Directory of Open Access Journals (Sweden)

    Desheng Liu

    2015-06-01

    Full Text Available Two novel schemes are proposed to teleport an unknown two-level quantum state probabilistically when the sender and the receiver only have partial information about the quantum channel, respectively. This is distinct from the fact that either the sender or the receiver has entire information about the quantum channel in previous schemes for probabilistic teleportation. Theoretical analysis proves that these schemes are straightforward, efficient and cost-saving. The concrete realization procedures of our schemes are presented in detail, and the result shows that our proposals could extend the application range of probabilistic teleportation.

  20. Controlled Teleportation of Multi-Qudit Quantum Information

    Institute of Scientific and Technical Information of China (English)

    JI Hua; ZHAN Xiao-Gui; ZENG Hao-Sheng

    2007-01-01

    We present a controlled teleportation scheme for teleporting an arbitrary superposition state of an M-qudit quantum system. The scheme employs only one entangled state as quantum channel, which consists of the qudits from Alice, Bob and every agent. The quantum operations used in the teleportation process are a series of qudit Bell measurements, single-qudit projective measurements, qudit H-gates, qudit-Pauli gates and qudit phase gates. It is shown that the original state can be restored by the receiver only on the condition that all the agents collaborate. If any agent does not cooperate, the original state can not be fully recovered.

  1. Teleported State and its Fidelity in Quantum Teleportation of Continuous Variables

    Institute of Scientific and Technical Information of China (English)

    LI Fu-Li; LI Hong-Rong; ZHANG Jun-Xiang; ZHU Shi-Yao

    2003-01-01

    When given an unknown quantum state which may be either a pure or a mixed state in the coherent state representation, we show that explicit expressions for the teleported state and its fidelity in the teleportation process (S. L. Braunstein and H. J. Kimble 1998 Phys. Rev. Lett. 80 869) can be obtained without explicit expansions for the two-mode squeezed vacuum state and the Bell basis in a specified representation.

  2. Quantum Teleportation with an Accelerated Observer and Black Hole Information

    CERN Document Server

    Shiokawa, K

    2009-01-01

    Nonperturbative analysis of quantum entanglement and quantum teleportation protocol using oscillator variables carried by observers in relativistic motion under the continuous influence of the environment is given. The full time evolution of quantum entanglement among static and accelerated observers is studied. The environment plays a dual role. While it creates bipartite and tripartite entanglement among observers even when the initial state is separable, it suppresses the entanglement via decoherence. Motivated by the black hole information problem, we consider quantum teleportation between static and accelerated observers. Acceleration of the observer suppresses fidelity of teleportation. Some of the quantum information escapes outside of the horizon in the form of bipartite and tripartite entanglement during the teleportation process. Explicit calculation of information loss is provided. In addition to the loss due to the interaction with the environment, there is an intrinsic loss originated in a measur...

  3. Teleportation-based continuous variable quantum cryptography

    Science.gov (United States)

    Luiz, F. S.; Rigolin, Gustavo

    2017-03-01

    We present a continuous variable (CV) quantum key distribution (QKD) scheme based on the CV quantum teleportation of coherent states that yields a raw secret key made up of discrete variables for both Alice and Bob. This protocol preserves the efficient detection schemes of current CV technology (no single-photon detection techniques) and, at the same time, has efficient error correction and privacy amplification schemes due to the binary modulation of the key. We show that for a certain type of incoherent attack, it is secure for almost any value of the transmittance of the optical line used by Alice to share entangled two-mode squeezed states with Bob (no 3 dB or 50% loss limitation characteristic of beam splitting attacks). The present CVQKD protocol works deterministically (no postselection needed) with efficient direct reconciliation techniques (no reverse reconciliation) in order to generate a secure key and beyond the 50% loss case at the incoherent attack level.

  4. Quantum teleportation over 143 kilometres using active feed-forward.

    Science.gov (United States)

    Ma, Xiao-Song; Herbst, Thomas; Scheidl, Thomas; Wang, Daqing; Kropatschek, Sebastian; Naylor, William; Wittmann, Bernhard; Mech, Alexandra; Kofler, Johannes; Anisimova, Elena; Makarov, Vadim; Jennewein, Thomas; Ursin, Rupert; Zeilinger, Anton

    2012-09-13

    The quantum internet is predicted to be the next-generation information processing platform, promising secure communication and an exponential speed-up in distributed computation. The distribution of single qubits over large distances via quantum teleportation is a key ingredient for realizing such a global platform. By using quantum teleportation, unknown quantum states can be transferred over arbitrary distances to a party whose location is unknown. Since the first experimental demonstrations of quantum teleportation of independent external qubits, an internal qubit and squeezed states, researchers have progressively extended the communication distance. Usually this occurs without active feed-forward of the classical Bell-state measurement result, which is an essential ingredient in future applications such as communication between quantum computers. The benchmark for a global quantum internet is quantum teleportation of independent qubits over a free-space link whose attenuation corresponds to the path between a satellite and a ground station. Here we report such an experiment, using active feed-forward in real time. The experiment uses two free-space optical links, quantum and classical, over 143 kilometres between the two Canary Islands of La Palma and Tenerife. To achieve this, we combine advanced techniques involving a frequency-uncorrelated polarization-entangled photon pair source, ultra-low-noise single-photon detectors and entanglement-assisted clock synchronization. The average teleported state fidelity is well beyond the classical limit of two-thirds. Furthermore, we confirm the quality of the quantum teleportation procedure without feed-forward by complete quantum process tomography. Our experiment verifies the maturity and applicability of such technologies in real-world scenarios, in particular for future satellite-based quantum teleportation.

  5. Entanglement diversion and quantum teleportation of entangled coherent states

    Institute of Scientific and Technical Information of China (English)

    Cai Xin-Hua; Guo Jie-Rong; Nie Jian-Jun; Jia Jin-Ping

    2006-01-01

    The proposals on entanglement diversion and quantum teleportation of entangled coherent states are presented.In these proposals,the entanglement between two coherent states,|α〉and |-α〉,with the same amplitude but a phase difference of π is utilized as a quantum channel.The processes of the entanglement diversion and the teleportation are achieved by using the 5050 symmetric beam splitters,the phase shifters and the photodetectors with the help of classical information.

  6. A group signature scheme based on quantum teleportation

    Energy Technology Data Exchange (ETDEWEB)

    Wen Xiaojun; Tian Yuan; Ji Liping; Niu Xiamu, E-mail: wxjun36@gmail.co [Information Countermeasure Technique Research Institute, Harbin Institute of Technology, Harbin 150001 (China)

    2010-05-01

    In this paper, we present a group signature scheme using quantum teleportation. Different from classical group signature and current quantum signature schemes, which could only deliver either group signature or unconditional security, our scheme guarantees both by adopting quantum key preparation, quantum encryption algorithm and quantum teleportation. Security analysis proved that our scheme has the characteristics of group signature, non-counterfeit, non-disavowal, blindness and traceability. Our quantum group signature scheme has a foreseeable application in the e-payment system, e-government, e-business, etc.

  7. Quantum teleportation with a quantum dot single photon source.

    Science.gov (United States)

    Fattal, D; Diamanti, E; Inoue, K; Yamamoto, Y

    2004-01-23

    We report the experimental demonstration of a quantum teleportation protocol with a semiconductor single photon source. Two qubits, a target and an ancilla, each defined by a single photon occupying two optical modes (dual-rail qubit), were generated independently by the single photon source. Upon measurement of two modes from different qubits and postselection, the state of the two remaining modes was found to reproduce the state of the target qubit. In particular, the coherence between the target qubit modes was transferred to the output modes to a large extent. The observed fidelity is 80%, in agreement with the residual distinguishability between consecutive photons from the source. An improved version of this teleportation scheme using more ancillas is the building block of the recent Knill, Laflamme, and Milburn proposal for efficient linear optics quantum computation.

  8. Opportunistic quantum network coding based on quantum teleportation

    Science.gov (United States)

    Shang, Tao; Du, Gang; Liu, Jian-wei

    2016-04-01

    It seems impossible to endow opportunistic characteristic to quantum network on the basis that quantum channel cannot be overheard without disturbance. In this paper, we propose an opportunistic quantum network coding scheme by taking full advantage of channel characteristic of quantum teleportation. Concretely, it utilizes quantum channel for secure transmission of quantum states and can detect eavesdroppers by means of quantum channel verification. What is more, it utilizes classical channel for both opportunistic listening to neighbor states and opportunistic coding by broadcasting measurement outcome. Analysis results show that our scheme can reduce the times of transmissions over classical channels for relay nodes and can effectively defend against classical passive attack and quantum active attack.

  9. Entanglement and quantum teleportation via decohered tripartite entangled states

    Energy Technology Data Exchange (ETDEWEB)

    Metwally, N., E-mail: nmohamed31@gmail.com

    2014-12-15

    The entanglement behavior of two classes of multi-qubit system, GHZ and GHZ like states passing through a generalized amplitude damping channel is discussed. Despite this channel causes degradation of the entangled properties and consequently their abilities to perform quantum teleportation, one can always improve the lower values of the entanglement and the fidelity of the teleported state by controlling on Bell measurements, analyzer angle and channel’s strength. Using GHZ-like state within a generalized amplitude damping channel is much better than using the normal GHZ-state, where the decay rate of entanglement and the fidelity of the teleported states are smaller than those depicted for GHZ state.

  10. Unity gain and non-unity gain quantum teleportation

    CERN Document Server

    Bowen, W P; Buchler, B C; Schnabel, R; Ralph, T C; Symul, T; Lam, P K

    2003-01-01

    We investigate continuous variable quantum teleportation. We discuss the methods presently used to characterize teleportation in this regime, and propose an extension of the measures proposed by Grangier and Grosshans \\cite{Grangier00}, and Ralph and Lam \\cite{Ralph98}. This new measure, the gain normalized conditional variance product $\\mathcal{M}$, turns out to be highly significant for continuous variable entanglement swapping procedures, which we examine using a necessary and sufficient criterion for entanglement. We elaborate on our recent experimental continuous variable quantum teleportation results \\cite{Bowen03}, demonstrating success over a wide range of teleportation gains. We analyze our results using fidelity; signal transfer, and the conditional variance product; and a measure derived in this paper, the gain normalized conditional variance product.

  11. Quantum teleportation and Kerr-Newman spacetime

    Institute of Scientific and Technical Information of China (English)

    Ge Xian-Hui; Shen You-Gen

    2005-01-01

    We consider the teleportation in the background of Kerr-Newman spacetime. Because of the Hawking effect, the fidelity of the teleportation is reduced. The results also show the fidelity is closely related to the mass, charge and rotating velocity of the black hole: high fidelity can be reached for massive, slowly rotating Kerr-Newman black holes.

  12. Optimal path for a quantum teleportation protocol in entangled networks

    Science.gov (United States)

    di Franco, C.; Ballester, D.

    2012-01-01

    Bellman's optimality principle has been of enormous importance in the development of whole branches of applied mathematics, computer science, optimal control theory, economics, decision making, and classical physics. Examples are numerous: dynamic programming, Markov chains, stochastic dynamics, calculus of variations, and the brachistochrone problem. Here we show that Bellman's optimality principle is violated in a teleportation problem on a quantum network. This implies that finding the optimal fidelity route for teleporting a quantum state between two distant nodes on a quantum network with bipartite entanglement will be a tough problem and will require further investigation.

  13. Quantum Standard Teleportation Based on the Generic Measurement Bases

    Institute of Scientific and Technical Information of China (English)

    HAO San-Ru; HOU Bo-Yu; XI Xiao-Qiang; YUE Rui-Hong

    2003-01-01

    We study the quantum standard teleportation based on the generic measurement bases. It is shown that the quantum standard teleportation does not depend on the explicit expression of the measurement bases. We have giventhe correspondence relation between the measurement performed by Alice and the unitary transformation performed byBob. We also prove that the single particle unknown states and the two-particle unknown cat-like states can be exactlytransmitted by means of the generic measurement bases and the correspondence unitary transformations.

  14. Quantum Standard Teleportation Based on the Generic Measurement Bases

    Institute of Scientific and Technical Information of China (English)

    HAOSan-Ru; HOUBo-Yu; XIXiao-Qiang; YUERui-Hong

    2003-01-01

    We study the quantum standard teleportation based on the generic measurement bases. It is shown that the quantum standard teleportation does not depend on the explicit expression of the measurement bases. We have given the correspondence relation between the measurement performed by Alice and the unitary transformation performed by Bob. We also prove that the single particle unknown states and the two-particle unknown cat-like states can be exactly transmitted by means of the generic measurement bases and the correspondence unitary transformations.

  15. Quantum teleportation by entanglement swapping with trapped ions

    Institute of Scientific and Technical Information of China (English)

    Zheng Xiao-Juan; Fang Mao-Fa; Cai Jian-Wu; Liao Xiang-Ping

    2006-01-01

    An effective teleportation scheme for an unknown ionic internal state via trapped ions is proposed without joint Bell-state measurement (BSM). In the constructed quantum channel process, we make use of entanglement swapping to avoid decrease in entanglement during the distributing of particles. Thus our scheme provides new prospects for quantum teleportation in a longer distance. The distinct advantage of our scheme is insensitive to the heating of vibrational mode. Furthermore, our scheme has no any individual optical access, and the successful probability also can reach 1.

  16. Network Coding-Based Communications via the Controlled Quantum Teleportation

    Directory of Open Access Journals (Sweden)

    Ying Guo

    2013-02-01

    Full Text Available Inspired by the structure of the network coding over the butterfly network, a framework of quantum network coding scheme is investigated, which transmits two unknown quantum states crossly over the butterfly quantum system with the multi-photon non-maximally entangled GHZ states. In this scheme, it contains certain number of entanglement-qubit source nodes that teleport unknown quantum states to other nodes on the small-scale network where each intermediate node can pass on its received quantum states to others via superdense coding. In order to transmit the unknown states in a deterministic way, the controlled quantum teleportation is adopted on the intermediate node. It makes legal nodes more convenient than any other previous teleportation schemes to transmit unknown quantum states to unknown participants in applications. It shows that the intrinsic efficiency of transmissions approaches 100% in principle. This scheme is secure based on the securely-shared quantum channels between all nodes and the quantum mechanical impossibility of local unitary transformations between non-maximally entangled GHZ states. Moreover, the generalized scheme is proposed for transmitting two multipartite entangled states.

  17. Quantum Entanglement: Separability, Measure, Fidelity of Teleportation, and Distillation

    Directory of Open Access Journals (Sweden)

    Ming Li

    2010-01-01

    Full Text Available Quantum entanglement plays crucial roles in quantum information processing. Quantum entangled states have become the key ingredient in the rapidly expanding field of quantum information science. Although the nonclassical nature of entanglement has been recognized for many years, considerable efforts have been taken to understand and characterize its properties recently. In this review, we introduce some recent results in the theory of quantum entanglement. In particular separability criteria based on the Bloch representation, covariance matrix, normal form and entanglement witness, lower bounds, subadditivity property of concurrence and tangle, fully entangled fraction related to the optimal fidelity of quantum teleportation, and entanglement distillation will be discussed in detail.

  18. Quantum Teleportation and Grover's Algorithm Without the Wavefunction

    Science.gov (United States)

    Niestegge, Gerd

    2017-01-01

    In the same way as the quantum no-cloning theorem and quantum key distribution in two preceding papers, entanglement-assisted quantum teleportation and Grover's search algorithm are generalized by transferring them to an abstract setting, including usual quantum mechanics as a special case. This again shows that a much more general and abstract access to these quantum mechanical features is possible than commonly thought. A non-classical extension of conditional probability and, particularly, a very special type of state-independent conditional probability are used instead of Hilbert spaces and wavefunctions.

  19. Quantum Teleportation and Grover's Algorithm Without the Wavefunction

    Science.gov (United States)

    Niestegge, Gerd

    2017-02-01

    In the same way as the quantum no-cloning theorem and quantum key distribution in two preceding papers, entanglement-assisted quantum teleportation and Grover's search algorithm are generalized by transferring them to an abstract setting, including usual quantum mechanics as a special case. This again shows that a much more general and abstract access to these quantum mechanical features is possible than commonly thought. A non-classical extension of conditional probability and, particularly, a very special type of state-independent conditional probability are used instead of Hilbert spaces and wavefunctions.

  20. EPR Pairs, Local Projections and Quantum Teleportation in Holography

    CERN Document Server

    Numasawa, Tokiro; Takayanagi, Tadashi; Watanabe, Kento

    2016-01-01

    In this paper we analyze three quantum operations in two dimensional conformal field theories (CFTs): local projection measurements, creations of partial entanglement between two CFTs, and swapping of subsystems between two CFTs. We also give their holographic duals and study time evolutions of entanglement entropy. By combining these operations, we present an analogue of quantum teleportation between two CFTs and give its holographic realization. We introduce a new quantity to probe tripartite entanglement by using local projection measurement.

  1. EPR pairs, local projections and quantum teleportation in holography

    Science.gov (United States)

    Numasawa, Tokiro; Shiba, Noburo; Takayanagi, Tadashi; Watanabe, Kento

    2016-08-01

    In this paper we analyze three quantum operations in two dimensional conformal field theories (CFTs): local projection measurements, creations of partial entanglement between two CFTs, and swapping of subsystems between two CFTs. We also give their holographic duals and study time evolutions of entanglement entropy. By combining these operations, we present an analogue of quantum teleportation between two CFTs and give its holographic realization. We introduce a new quantity to probe tripartite entanglement by using local projection measurement.

  2. Quantum teleportation from a telecom-wavelength photon to a solid-state quantum memory

    Energy Technology Data Exchange (ETDEWEB)

    Bussieres, Felix [Group of Applied Physics, University of Geneva (Switzerland)

    2014-07-01

    Quantum teleportation is a cornerstone of quantum information science due to its essential role in several important tasks such as the long-distance transmission of quantum information using quantum repeaters. In this context, a challenge of paramount importance is the distribution of entanglement between remote nodes, and to use this entanglement as a resource for long-distance light-to-matter quantum teleportation. In this talk I will report on the demonstration of quantum teleportation of the polarization state of a telecom-wavelength photon onto the state of a solid-state quantum memory. Entanglement is established between a rare-earth-ion doped crystal storing a single photon that is polarization-entangled with a flying telecom-wavelength photon. The latter is jointly measured with another flying qubit carrying the polarization state to be teleported, which heralds the teleportation. The fidelity of the polarization state of the photon retrieved from the memory is shown to be greater than the maximum fidelity achievable without entanglement, even when the combined distances travelled by the two flying qubits is 25 km of standard optical fibre. This light-to-matter teleportation channel paves the way towards long-distance implementations of quantum networks with solid-state quantum memories.

  3. Probabilistic quantum teleportation in the presence of noise

    Science.gov (United States)

    Fortes, Raphael; Rigolin, Gustavo

    2016-06-01

    We extend the research program initiated in [Phys. Rev. A 92, 012338 (2015), 10.1103/PhysRevA.92.012338] from noisy deterministic teleportation protocols to noisy probabilistic (conditional) protocols. Our main goal now is to study how we can increase the fidelity of the teleported state in the presence of noise by working with probabilistic protocols. We work with several scenarios involving the most common types of noise in realistic implementations of quantum communication tasks and find many cases where adding more noise to the probabilistic protocol increases considerably the fidelity of the teleported state, without decreasing the probability of a successful run of the protocol. Also, there are cases where the entanglement of the channel connecting Alice and Bob leading to the greatest fidelity is not maximal. Moreover, there exist cases where the optimal fidelity for the probabilistic protocols are greater than the maximal fidelity (2 /3 ) achievable by using only classical resources, while the optimal ones for the deterministic protocols under the same conditions lie below this limit. This result clearly illustrates that in some cases we can only get a truly quantum teleportation if we use probabilistic instead of deterministic protocols.

  4. Controlled teleportation of multi-qudit quantum information

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    We propose a scheme for realizing a controlled teleportation of random M-qudit quantum information under the control of N agents. The resource consumption includes a prearranged (2M + N + 1)-qudit entangled quantum channel and (2M + N + 1) log2 d-bit classical communication. And the quantum operations used in the teleportation process are a series of generalized Bell-state measurements, single-qudit measurements, qudit H-gates, qudit-Pauli gates and qudit phase gates. It is shown that the original state can be restored by the receiver only on condition that all the agents work in collaboration with each others. If one agent does not cooperate with the other, the original state cannot be fully recovered.

  5. Scheme for teleporting an unknown atomic state to any node in a quantum communication network

    Institute of Scientific and Technical Information of China (English)

    宋克慧; 张为俊; 郭光灿

    2002-01-01

    We propose a scheme for teleporting an unknown atomic state. In order to realize the teleportation to any node ina quantum communication network, an n-atom Greenberger-Horne-Zeilinger (GHZ) state is needed, which is utilizedas the quantum channel. From this n-atom GHZ state, two-node entanglement of processing and receiving teleportedstates can be obtained through the quantum logic gate manipulation. Finally, for the unequally weighted GHZ state,probabilistic teleportation is shown.

  6. Quantum logic networks for controlled teleportation of a single particle via W state

    Institute of Scientific and Technical Information of China (English)

    Yuan Hong-Chun; Qi Kai-Guo

    2005-01-01

    We discuss the scheme for probabilistic and controlled teleportation of an unknown state of one particle using the general three-particle W state as the quantum channel. The feature of this scheme is that teleportation between two sides depends on the agreement of the third side (Charlie), who may participate the process of quantum teleportation as a supervisor. In addition, we also construct efficient quantum logic networks for implementing the new scheme by means of the primitive operations.

  7. Quantum chance nonlocality, teleportation and other quantum marvels

    CERN Document Server

    Gisin, Nicolas

    2014-01-01

    Quantum physics, which offers an explanation of the world on the smallest scale, has fundamental implications that pose a serious challenge to ordinary logic. Particularly counterintuitive is the notion of entanglement, which has been explored for the past 30 years and posits an ubiquitous randomness capable of manifesting itself simultaneously in more than one place. This amazing 'non-locality' is more than just an abstract curiosity or paradox: it has entirely down-to-earth applications in cryptography, serving for example to protect financial information; it also has enabled the demonstration of 'quantum teleportation', whose infinite possibilities even science-fiction writers can scarcely imagine. This delightful and concise exposition does not avoid the deep logical difficulties of quantum physics, but gives the reader the insights needed to appreciate them . From 'Bell's Theorem' to experiments in quantum entanglement, the reader will gain a solid understanding of one of the most fascinating ar...

  8. Quantum multi-signature protocol based on teleportation

    Energy Technology Data Exchange (ETDEWEB)

    Wen Xiao-jun; Liu Yun; Sun Yu [Beijing Jiaotong Univ., Beijing (China). School of Electronic Information Engineering

    2007-03-15

    In this paper, a protocol which can be used in multi-user quantum signature is proposed. The scheme of signature and verification is based on the correlation of Greenberger-Horne-Zeilinger (GHZ) states and the controlled quantum teleportation. Different from the digital signatures, which are based on computational complexity, the proposed protocol has perfect security in the noiseless quantum channels. Compared to previous quantum signature schemes, this protocol can verify the signature independent of an arbitrator as well as realize multi-user signature together. (orig.)

  9. Continuous-variable quantum teleportation of even and odd coherent states through varied gain channels

    Institute of Scientific and Technical Information of China (English)

    Li Ying; Zhang Jing; Zhang Jun-Xiang; Zhang Tian-Cai

    2006-01-01

    This paper has investigated quantum teleportation of even and odd coherent states in terms of the EPR entanglement states for continuous variables. It discusses the relationship between the fidelity and the entanglement of EPR states, which is characterized by the degree of squeezing and the gain of classical channels. It shows that the quality of teleporting quantum states also depends on the characteristics of the states themselves. The properties of teleporting even and odd coherent states at different intensities are investigated. The difference of teleporting two such kinds of quantum states are analysed based on the quantum distance function.

  10. Quantum Logic Networks for Probabilistic and Controlled Teleportation of Unknown Quantum States

    Institute of Scientific and Technical Information of China (English)

    GAO Ting

    2004-01-01

    We present simplification schemes for probabilistic and controlled teleportation of the unknown quantum states of both one particle and two particles and construct efficient quantum logic networks for implementing the new schemes by means of the primitive operations consisting of single-qubit gates, two-qubit controlled-not gates, Von Neumann measurement, and classically controlled operations. In these schemes the teleportation are not always successful but with certain probability.

  11. Monogamy relation in multipartite continuous-variable quantum teleportation

    Science.gov (United States)

    Lee, Jaehak; Ji, Se-Wan; Park, Jiyong; Nha, Hyunchul

    2016-12-01

    Quantum teleportation (QT) is a fundamentally remarkable communication protocol that also finds many important applications for quantum informatics. Given a quantum entangled resource, it is crucial to know to what extent one can accomplish the QT. This is usually assessed in terms of output fidelity, which can also be regarded as an operational measure of entanglement. In the case of multipartite communication when each communicator possesses a part of an N -partite entangled state, not all pairs of communicators can achieve a high fidelity due to the monogamy property of quantum entanglement. We here investigate how such a monogamy relation arises in multipartite continuous-variable (CV) teleportation, particularly when using a Gaussian entangled state. We show a strict monogamy relation, i.e., a sender cannot achieve a fidelity higher than optimal cloning limit with more than one receiver. While this seems rather natural owing to the no-cloning theorem, a strict monogamy relation still holds even if the sender is allowed to individually manipulate the reduced state in collaboration with each receiver to improve fidelity. The local operations are further extended to non-Gaussian operations such as photon subtraction and addition, and we demonstrate that the Gaussian cloning bound cannot be beaten by more than one pair of communicators. Furthermore, we investigate a quantitative form of monogamy relation in terms of teleportation capability, for which we show that a faithful monogamy inequality does not exist.

  12. Quantum teleportation of multiple degrees of freedom of a single photon

    Science.gov (United States)

    Wang, Xi-Lin; Cai, Xin-Dong; Su, Zu-En; Chen, Ming-Cheng; Wu, Dian; Li, Li; Liu, Nai-Le; Lu, Chao-Yang; Pan, Jian-Wei

    2015-02-01

    Quantum teleportation provides a `disembodied' way to transfer quantum states from one object to another at a distant location, assisted by previously shared entangled states and a classical communication channel. As well as being of fundamental interest, teleportation has been recognized as an important element in long-distance quantum communication, distributed quantum networks and measurement-based quantum computation. There have been numerous demonstrations of teleportation in different physical systems such as photons, atoms, ions, electrons and superconducting circuits. All the previous experiments were limited to the teleportation of one degree of freedom only. However, a single quantum particle can naturally possess various degrees of freedom--internal and external--and with coherent coupling among them. A fundamental open challenge is to teleport multiple degrees of freedom simultaneously, which is necessary to describe a quantum particle fully and, therefore, to teleport it intact. Here we demonstrate quantum teleportation of the composite quantum states of a single photon encoded in both spin and orbital angular momentum. We use photon pairs entangled in both degrees of freedom (that is, hyper-entangled) as the quantum channel for teleportation, and develop a method to project and discriminate hyper-entangled Bell states by exploiting probabilistic quantum non-demolition measurement, which can be extended to more degrees of freedom. We verify the teleportation for both spin-orbit product states and hybrid entangled states, and achieve a teleportation fidelity ranging from 0.57 to 0.68, above the classical limit. Our work is a step towards the teleportation of more complex quantum systems, and demonstrates an increase in our technical control of scalable quantum technologies.

  13. Optimal path for a quantum teleportation protocol in entangled networks

    OpenAIRE

    Di Franco, C.; Ballester, D.

    2010-01-01

    Bellman's optimality principle has been of enormous importance in the development of whole branches of applied mathematics, computer science, optimal control theory, economics, decision making, and classical physics. Examples are numerous: dynamic programming, Markov chains, stochastic dynamics, calculus of variations, and the brachistochrone problem. Here we show that Bellman's optimality principle is violated in a teleportation problem on a quantum network. This implies that finding the opt...

  14. Quantum Teleportation and Superdense Coding via W-Class States

    Institute of Scientific and Technical Information of China (English)

    YAN Jun; WU Huai-Zhi; YANG Zhen-Biao; ZHENG Shi-Biao

    2008-01-01

    According to the protocol of Agrawal et al., we propose a cavity QED scheme for realization of teleportation and dense coding. Instead of using EPR states and GHZ states, our scheme is more insensitive to the loss of one particle by using a W-class state as a quantum channel. Besides, our scheme is immune to thermal field, and does not require the cavity to remain in the vacuum state throughout the procedure.

  15. Continuous variable quantum teleportation with a finite-basis entanglement resource

    CERN Document Server

    Kurzeja, S I J

    2002-01-01

    Entanglement is a crucial resource in quantum information theory. We investigate the use of different forms of entangled states in continuous variable quantum teleportation, specifically the use of a finite-basis entanglement resource. We also consider the continuous variable teleportation of finite-basis states, such as qubits, and present results that point to the possibility of an efficient conditional scheme for continuous variable teleportation of such states with near-unit fidelity using finite-basis entanglement.

  16. Influence of Non-Uniform Magnetic Field on Quantum Teleportation in Heisenberg XY Model

    Institute of Scientific and Technical Information of China (English)

    SHAO Bin; YANG Tie-jian; ZHAO Yue-hong; ZOU Jian

    2007-01-01

    By considering the intrinsic decoherence, the validity of quantum teleportation of a two-qubit 1D Heisenberg XY chain in a non-uniform external magnetic field is studied. The fidelity as the measurement of a possible quantum teleportation is calculated and the effects of the non-uniform magnetic field and the intrinsic decoherence are discussed. It is found that anti-parallel magnetic field is more favorable for teleportation and the fidelity is suppressed by the intrinsic decoherence.

  17. Probabilistic Teleportation of an Arbitrary Two-Particle State and Its Quantum Circuits

    Institute of Scientific and Technical Information of China (English)

    GUO Zhan-Ying; FANG Jian-Xing; ZHU Shi-Qun; QIAN Xue-Min

    2006-01-01

    Two simple schemes for probabilistic teleportation of an arbitrary unknown two-particle state using a non-maximally entangled EPR pair and a non-maximally entangled GHZ state as quantum channels are proposed.After receiving Alice's Bell state measurement results, Bob performs a collective unitary transformation on his inherent particles without introducing the auxiliary qubit. The original state can be probabilistically teleported. Meanwhile,quantum circuits for realization of successful teleportation are also presented.

  18. Application of Bipartite and Tripartite Entangled State Representations in Quantum Teleportation of Continuous Variables

    Institute of Scientific and Technical Information of China (English)

    YUAN Hong-Chun; QI Kai-Guo

    2005-01-01

    We mostly investigate two schemes. One is to teleport a multi-mode W-type entangled coherent state using a peculiar bipartite entangled state as the quantum channel different from other proposals. Based on our formalism,teleporting multi-mode coherent state or squeezed state is also possible. Another is that the tripartite entangled state is used as the quantum channel of controlled teleportation of an arbitrary and unknown continuous variable in the case of three participators.

  19. Quantum teleportation from light beams to vibrational states of a macroscopic diamond

    Science.gov (United States)

    Hou, P.-Y.; Huang, Y.-Y.; Yuan, X.-X.; Chang, X.-Y.; Zu, C.; He, L.; Duan, L.-M.

    2016-05-01

    With the recent development of optomechanics, the vibration in solids, involving collective motion of trillions of atoms, gradually enters into the realm of quantum control. Here, building on the recent remarkable progress in optical control of motional states of diamonds, we report an experimental demonstration of quantum teleportation from light beams to vibrational states of a macroscopic diamond under ambient conditions. Through quantum process tomography, we demonstrate average teleportation fidelity (90.6+/-1.0)%, clearly exceeding the classical limit of 2/3. The experiment pushes the target of quantum teleportation to the biggest object so far, with interesting implications for optomechanical quantum control and quantum information science.

  20. Probabilistic Teleportation of Multi-particle d-Level Quantum State

    Institute of Scientific and Technical Information of China (English)

    CAO Min; ZHU Shi-Qun

    2005-01-01

    The general scheme for teleportation of a multi-particle d-level quantum state is presented when m pairs of partially entangled particles are utilized as quantum channels. The probabilistic teleportation can be achieved with a successful probability of d-1∏N=0(CN0)2/dM,which is determined by the smallest coefficients of each entangled channels.

  1. Teleportation with an Arbitrary Mixed Resource as a Trace-Preserving Quantum Channel

    Institute of Scientific and Technical Information of China (English)

    Sergio Albeverio; FEI Shao-Ming; YANG Wen-Li

    2002-01-01

    General conditions are given in order to perform a perfect teleportation process in the case where theHilbert spaces involved have different dimensions. An explicit expression is obtained for the quantum channel associatedwith the standard teleportation protocol To with an arbitrary mixed state resource. The transmission fidelity of thecorresponding quantum channel is given.

  2. Four-level quantum teleportation, swapping and collective translations of multipartite quantum entanglement

    CERN Document Server

    Zhong, Z Z

    2004-01-01

    In this paper, a new optimal scheme of four-level quantum teleportation and swapping of quantum entanglement is given, i.e. we construct a perfect complete orthogonal basis of the bipartite ququadrit systems, by using of this basis the four-level quantum teleportations and the swapping can be conclusively achieved according to the standard steps. Further, the above bases are associated to the unextendible product bases (UPB) and the exact entanglement bases (EEB), then in the $2\\times 2\\times 2$ systems and in the $3\\times 3$ systems we can achieve the collective translations of multipartite quantum entanglement.

  3. Quantum Teleportation via Completely Anisotropic Heisenberg Chain in Inhomogeneous Magnetic Field

    Institute of Scientific and Technical Information of China (English)

    FU Cheng-Hua; HU Zhan-Ning

    2013-01-01

    The quantum teleportation with the entangled thermal state is investigated based on the completely anisotropic Heisenberg chain in the presence of the externally inhomogeneous magnetic field.The effects of the anisotropy and magnetic field for the quantum fidefity are studied in detail.The zero temperature limit and the features of the nonzero temperature for this nonclassical fidelity are obtained.We find that the quantum teleportation demands more stringent conditions than the thermal entanglement of the resource by investigating the threshold temperature of the thermal concurrence and the critical temperature of the maximal teleportation fidelity.The useful quantum teleportation should avoid the point of the phase transition of the system and the anisotropy of the chain and the external magnetic field can control the applicability of the resource in the quantum teleportation.

  4. Teleportation-based realization of an optical quantum two-qubit entangling gate

    CERN Document Server

    Gao, Wei-Bo; Lu, Chao-Yang; Dai, Han-Ning; Wagenknecht, Claudia; Zhang, Qiang; Zhao, Bo; Peng, Cheng-Zhi; Chen, Zeng-Bing; Chen, Yu-Ao; Pan, Jian-Wei

    2010-01-01

    In recent years, there has been heightened interest in quantum teleportation, which allows for the transfer of unknown quantum states over arbitrary distances. Quantum teleportation not only serves as an essential ingredient in long-distance quantum communication, but also provides enabling technologies for practical quantum computation. Of particular interest is the scheme proposed by Gottesman and Chuang [Nature \\textbf{402}, 390 (1999)], showing that quantum gates can be implemented by teleporting qubits with the help of some special entangled states. Therefore, the construction of a quantum computer can be simply based on some multi-particle entangled states, Bell state measurements and single-qubit operations. The feasibility of this scheme relaxes experimental constraints on realizing universal quantum computation. Using two different methods we demonstrate the smallest non-trivial module in such a scheme---a teleportation-based quantum entangling gate for two different photonic qubits. One uses a high-...

  5. Quantum repeaters using continuous-variable teleportation

    Science.gov (United States)

    Dias, Josephine; Ralph, T. C.

    2017-02-01

    Quantum optical states are fragile and can become corrupted when passed through a lossy communication channel. Unlike for classical signals, optical amplifiers cannot be used to recover quantum signals. Quantum repeaters have been proposed as a way of reducing errors and hence increasing the range of quantum communications. Current protocols target specific discrete encodings, for example quantum bits encoded on the polarization of single photons. We introduce a more general approach that can reduce the effect of loss on any quantum optical encoding, including those based on continuous variables such as the field amplitudes. We show that in principle the protocol incurs a resource cost that scales polynomially with distance. We analyze the simplest implementation and find that while its range is limited it can still achieve useful improvements in the distance over which quantum entanglement of field amplitudes can be distributed.

  6. No-cloning theorem and teleportation criteria for quantum continuous variables

    CERN Document Server

    Grosshans, F; Grosshans, Fr\\'ed\\'eric; Grangier, Philippe

    2000-01-01

    We discuss the criteria presently used for evaluating the efficiency of quantum teleportation schemes for continuous variables. Using an argument based upon the difference between 1-to-2 quantum cloning (quantum duplication) and 1-to-infinity cloning (classical measurement), we show that a fidelity value larger than 2/3 is required for successful quantum teleportation of coherent states. This value has not been reached experimentally so far.

  7. Requirement of optical coherence for continuous-variable quantum teleportation.

    Science.gov (United States)

    Rudolph, T; Sanders, B C

    2001-08-13

    We show that the sender and the receiver each require coherent devices in order to achieve unconditional continuous variable quantum teleportation (CVQT), and this requirement cannot be achieved with conventional laser sources, linear optics, ideal photon detectors, and perfect Fock state sources. The appearance of successful CVQT in recent experiments is due to interpreting the measurement record fallaciously in terms of one preferred ensemble (or decomposition) of the correct density matrix describing the state. Our analysis is unrelated to technical problems such as laser phase drift or finite squeezing bandwidth.

  8. Optimal conclusive teleportation of a d-dimensional two-particle unknown quantum state

    Institute of Scientific and Technical Information of China (English)

    Yang Yu-Guang; Wen Qiao-Yan; Zhu Fu-Chen

    2006-01-01

    A conclusive teleportation protocol of a d-dimensional two-particle unknown quantum state using three ddimensional particles in an arbitrary pure state is proposed. A sender teleports the unknown state conclusively to a receiver by using the positive operator valued measure(POVM) and introducing an ancillary qudit to perform the generalized Bell basis measurement. We calculate the optimal teleportation fidelity. We also discuss and analyse the reason why the information on the teleported state is lost in the course of the protocol.

  9. Quantum teleportation from a telecom-wavelength photon to a solid-state quantum memory

    Science.gov (United States)

    Bussières, Félix; Clausen, Christoph; Tiranov, Alexey; Korzh, Boris; Verma, Varun B.; Nam, Sae Woo; Marsili, Francesco; Ferrier, Alban; Goldner, Philippe; Herrmann, Harald; Silberhorn, Christine; Sohler, Wolfgang; Afzelius, Mikael; Gisin, Nicolas

    2014-10-01

    Quantum teleportation is a cornerstone of quantum information science due to its essential role in important tasks such as the long-distance transmission of quantum information using quantum repeaters. This requires the efficient distribution of entanglement between remote nodes of a network. Here, we demonstrate quantum teleportation of the polarization state of a telecom-wavelength photon onto the state of a solid-state quantum memory. Entanglement is established between a rare-earth-ion-doped crystal storing a single photon that is polarization-entangled with a flying telecom-wavelength photon. The latter is jointly measured with another flying polarization qubit to be teleported, which heralds the teleportation. The fidelity of the qubit retrieved from the memory is shown to be greater than the maximum fidelity achievable without entanglement, even when the combined distances travelled by the two flying qubits is 25 km of standard optical fibre. Our results demonstrate the possibility of long-distance quantum networks with solid-state resources.

  10. Quantum Entanglement and Teleportation of Quantum-Dot States in Microcavities

    CERN Document Server

    Miranowicz, A; Liu, Yu-xi; Chimczak, G; Koashi, M; Imoto, N; 10.1380/ejssnt.2007.51

    2009-01-01

    Generation and control of quantum entanglement are studied in an equivalent-neighbor system of spatially-separated semiconductor quantum dots coupled by a single-mode cavity field. Generation of genuinely multipartite entanglement of qubit states realized by conduction-band electron-spin states in quantum dots is discussed. A protocol for quantum teleportation of electron-spin states via cavity decay is briefly described.

  11. A Quantum Proxy Weak Blind Signature Scheme Based on Controlled Quantum Teleportation

    Science.gov (United States)

    Cao, Hai-Jing; Yu, Yao-Feng; Song, Qin; Gao, Lan-Xiang

    2015-04-01

    Proxy blind signature is applied to the electronic paying system, electronic voting system, mobile agent system, security of internet, etc. A quantum proxy weak blind signature scheme is proposed in this paper. It is based on controlled quantum teleportation. Five-qubit entangled state functions as quantum channel. The scheme uses the physical characteristics of quantum mechanics to implement message blinding, so it could guarantee not only the unconditional security of the scheme but also the anonymity of the messages owner.

  12. Quantum Logic Networks for Probabilistic Teleportation of an Arbitrary Three-Particle State

    Institute of Scientific and Technical Information of China (English)

    QIAN Xue-Min; FANG Jian-Xing; ZHU Shi-Qun; XI Yong-Jun

    2005-01-01

    The scheme for probabilistic teleportation of an arbitrary three-particle state is proposed. By using single qubit gate and three two-qubit gates, efficient quantum logic networks for probabilistic teleportation of an arbitrary three-particle state are constructed.

  13. Quantum Teleportation of One-Photon and Two-Photon Superposition States

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    @@ One-photon and two-photon superposition states are the fundamental quantum states, which have shown interesting features, such as squeezing and anti-bunching. In this paper we discuss the quantum teleportation of such quantum states with the continuous-wave EPR states. Fidelity as a function of EPR correlation is obtained. We also compared the results with Fock state and coherent state teleportation.

  14. Quantum versus Classical Domains for Teleportation with Continuous Variables

    CERN Document Server

    Braunstein, S L; Kimble, H J; Van Loock, P; Braunstein, Samuel L.; Fuchs, Christopher A.

    2000-01-01

    Fidelity F{classical} = 1/2 has been established as setting the boundary between classical and quantum domains in the teleportation of coherent states of the electromagnetic field (S. L. Braunstein, C. A. Fuchs, and H. J. Kimble, J. Mod. Opt. 47, 267 (2000)). Two recent papers by P. Grangier and F. Grosshans (quant-ph/0009079 and quant-ph/0010107) introduce alternate criteria for setting this boundary and as a result claim that the appropriate boundary should be F = 2/3. Although larger fidelities would lead to enhanced teleportation capabilities, we show that the new conditions of Grangier and Grosshans are largely unrelated to the questions of entanglement and Bell-inequality violations that they take to be their primary concern. With regard to the quantum-classical boundary, we demonstrate that fidelity F{classical} = 1/2 remains the appropriate point of demarcation. The claims of Grangier and Grosshans to the contrary are simply wrong, as we show by an analysis of the conditions for nonseparability (that ...

  15. Fidelity of Quantum Teleportation for Single-Mode Squeezed State Light

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jun-Xiang; XIE Chang-De; PENG Kun-Chi

    2005-01-01

    @@ The fidelity of quantum teleportation of a single-mode squeezed state of light is calculated based on the general theory of quantum-mechanical measurement in the Schrodinger picture. It is shown that the criterion for the nonclassical state teleportation is different from that for coherent state. F = 1/2 is no longer the rigorous boundary between classical and quantum teleportation for a squeezed state of light. When the quantum entanglement of an Einstein-Podolsky-Rosen (EPR) beam used for teleportation and the parameters of the system are given,the fidelity depends on the squeezing of the input squeezed state. The higher the squeezing is, the smaller the fidelity is, and the lower the classical limitation of fidelity is. The dependence of the optimum gain for teleporting a squeezed vacuum state upon the EPR entanglement is also calculated. The results obtained provide important references for designing experimental systems of teleporting a non-classical state and judging the quality of the teleported quantum state.

  16. Exponentially enhanced quantum communication rate by multiplexing continuous-variable teleportation

    Science.gov (United States)

    Christ, Andreas; Lupo, Cosmo; Silberhorn, Christine

    2012-08-01

    A major challenge of today's quantum communication systems lies in the transmission of quantum information with high rates over long distances in the presence of unavoidable losses. Thereby the achievable quantum communication rate is fundamentally limited by the amount of energy that can be transmitted per use of the channel. It is hence vital to develop quantum communication protocols that encode quantum information as energy efficiently as possible. To this aim we investigate continuous-variable quantum teleportation as a method of distributing quantum information. We explore the possibility to encode information on multiple optical modes and derive upper and lower bounds on the achievable quantum channel capacities. This analysis enables us to benchmark single-mode versus multi-mode entanglement resources. Our research reveals that multiplexing does not only feature an enhanced energy efficiency, leading to an exponential increase in the achievable quantum communication rates in comparison to single-mode coding, but also yields an improved loss resilience. However, as reliable quantum information transfer is only achieved for entanglement values above a certain threshold a careful optimization of the number of coding modes is needed to obtain the optimal quantum channel capacity.

  17. Long-distance quantum teleportation assisted with free-space entanglement distribution

    Institute of Scientific and Technical Information of China (English)

    Ren Ji-Gang; Yang Bin; Yi Zhen-Huan; Zhou Fei; Chen Kai; Peng Cheng-Zhi; Pan Jian-Wei

    2009-01-01

    Faithful long-distance quantum teleportation necessitates prior entanglement distribution between two communicated locations.The particle carrying on the unknown quantum information is then combined with one particle of the entangled states for Bell-state measurements,which leads to a transfer of the original quantum information onto the other particle of the entangled states.However in most of the implemented teleportation experiments nowadays,the Bell-state measurements are performed even before successful distribution of entanglement.This leads to an instant collapse of the quantum state for the transmitted particle,which is actually a single-particle transmission thereafter.Thus the true distance for quantum teleportation is,in fact,only in a level of meters.In the present experiment we design a novel scheme which has overcome this limit by utilizing fiber as quantum memory.A complete quantum teleportation is achieved upon successful entanglement distribution over 967 meters in public free space.Active feed-forward control techniques are developed for real-time transfer of quantum information.The overall experimental fidelities for teleported states are better than 89.6%,which signify high-quality teleportation.

  18. Quantum teleportation from light beams to vibrational states of a macroscopic diamond

    Science.gov (United States)

    Hou, Panyu; Huang, Yuanyuan; Yuan, Xinxing; Chang, Xiuying; Zu, Chong; He, Li; Duan, Luming; CenterQuantum Information, IIIS, Tsinghua University, Beijing 100084, PR China Team; Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA Team

    2016-05-01

    Quantum teleportation is an unusual disembodied form of quantum information transfer through pre-shared entanglement and classical communication, which has found important applications for realization of various quantum technologies. It is of both fundamental interest and practical importance to push quantum teleportation towards macroscopic objects. With the recent development of optomechanics, the vibration in solids, involving collective motion of trillions of atoms, gradually enters into the realm of quantum control. Built on the recent remarkable progress in optical control of motional states in diamond, we report an experimental demonstration of quantum teleportation from light beams to vibrational states of a macroscopic diamond under ambient conditions. Through quantum state tomography, we demonstrate an average teleportation fidelity (90.6 +/- 1.0)%, exceeding the classical limit of 2/3. The experiment pushes the target of quantum teleportation to the biggest object so far, with interesting implications for quantum foundational studies, optomechanical quantum control and quantum information science. Center for Quantum Information, IIIS, Tsinghua University.

  19. Quantum Measurements using Diamond Spins: From Fundamental Tests to Long-Distance Teleportation

    NARCIS (Netherlands)

    Hanson, R.

    2014-01-01

    Spin qubits in diamond provide an excellent platform both for fundamental tests and for realizing extended quantum networks . Here we present our latest results, including the deterministic teleportation over three meters.

  20. Quantum broadcast scheme and multi-output quantum teleportation via four-qubit cluster state

    Science.gov (United States)

    Yu, Yan; Zha, Xin Wei; Li, Wei

    2017-02-01

    In this paper, two theoretical schemes of the arbitrary single-qubit states via four-qubit cluster state are proposed. One is three-party quantum broadcast scheme, which realizes the broadcast among three participants. The other is multi-output quantum teleportation. Both allow two distant receivers to simultaneously and deterministically obtain the arbitrary single-qubit states, respectively. Compared with former schemes of an arbitrary single-qubit state, the proposed schemes realize quantum multi-cast communication efficiently, which enables Bob and Charlie to obtain the states simultaneously in the case of just knowing Alice's measurement results. The proposed schemes play an important role in quantum information, specially in secret sharing and quantum teleportation.

  1. Improving the fidelity of continuous-variable quantum teleportation by tuning displacement gain

    Institute of Scientific and Technical Information of China (English)

    Jinming Liu(刘金明); Jian Li(李剑); Guangcan Guo(郭光灿)

    2003-01-01

    The fidelity of teleportation of continuous quantum variables can be improved by tuning the local displace-ment gain. We investigate the optimization of the fidelity for the teleportation of Schrodinger cat states,and of coherent states. It is found that the gain corresponding to the maximum fidelity is not equal to onefor the two input states in the case of the small squeezing degree of the entanglement resource, while unitydisplacement gain is the best choice for teleporting arbitrary quantum states in the case of large squeezing.

  2. Quantum teleportation and information splitting via four-qubit cluster state and a Bell state

    Science.gov (United States)

    Ramírez, Marlon David González; Falaye, Babatunde James; Sun, Guo-Hua; Cruz-Irisson, M.; Dong, Shi-Hai

    2017-10-01

    Quantum teleportation provides a "bodiless" way of transmitting the quantum state from one object to another, at a distant location, using a classical communication channel and a previously shared entangled state. In this paper, we present a tripartite scheme for probabilistic teleportation of an arbitrary single qubit state, without losing the information of the state being teleported, via a fourqubit cluster state of the form | ϕ>1234 = α|0000>+ β|1010>+ γ|0101>- η|1111>, as the quantum channel, where the nonzero real numbers α, β, γ, and η satisfy the relation j αj2 + | β|2 + | γ|2 + | η|2 = 1. With the introduction of an auxiliary qubit with state |0>, using a suitable unitary transformation and a positive-operator valued measure (POVM), the receiver can recreate the state of the original qubit. An important advantage of the teleportation scheme demonstrated here is that, if the teleportation fails, it can be repeated without teleporting copies of the unknown quantum state, if the concerned parties share another pair of entangled qubit. We also present a protocol for quantum information splitting of an arbitrary two-particle system via the aforementioned cluster state and a Bell-state as the quantum channel. Problems related to security attacks were examined for both the cases and it was found that this protocol is secure. This protocol is highly efficient and easy to implement.

  3. Controlled teleportation of high-dimension quantum-states with generalized Bell-state measurement

    Institute of Scientific and Technical Information of China (English)

    Zhan You-Bang

    2007-01-01

    In this paper a scheme for controlled teleportation of arbitrary high-dimensional unknown quantum states is proposed by using the generalized Bell-basis measurement and the generalized Hadamard transformation. As two special cases, two schemes of controlled teleportation of an unknown single-qutrit state and an unknown two-qutrit state are investigated in detail. In the first scheme, a maximally entangled three-qutrit state is used as the quantum channel, while in the second scheme, an entangled two-qutrit state and an entangled three-qutrit state are employed as the quantum channels. In these schemes, an unknown qutrit state can be teleported to either one of two receivers, but only one of them can reconstruct the qutrit state with the help of the other. Based on the case of qutrits, a scheme of controlled teleportation of an unknown qudit state is presented.

  4. Optimal Conclusive Teleportation of an Arbitrary d-Dimensional N-Particle Unknown State via a Partially Entangled Quantum Channel

    Institute of Scientific and Technical Information of China (English)

    HAO San-Ru; HOU Bo-Yu; XI Xiao-Qiang; YUE Rui-Hong

    2003-01-01

    In the paper we generalize the standard teleportation to the conclusive teleportation case which can teleportan arbitrary d-dimensional N-particle unknown state via the partially entangled quantum channel. We show that onlyif the quantum channel satisfies a constraint condition can the most general d-dimensional N-particle unknown state beperfect conclusively teleported. We also present a method for optimal conclusively teleportation of the N-particle statesand for constructing the joint POVM which can discern the quantum states on the sender's (Alice's) side. Two typicalexamples are given so that one can see how our method works.

  5. Quantum teleportation in the spin-orbit variables of photon pairs

    CERN Document Server

    Khoury, A Z

    2011-01-01

    We propose a polarization to orbital angular momentum teleportation scheme using entangled photon pairs generated by spontaneous parametric down conversion. By making a joint detection of the polarization and angular momentum parity of a single photon, we are able to detect all the Bell-states and perform, in principle, perfect teleportation from a discrete to a continuous system using minimal resources. The proposed protocol implementation demands experimental resources that are currently available in quantum optics laboratories.

  6. Scheme for deterministic Bell-state-measurement-free quantum teleportation

    CERN Document Server

    Yang, M; Yang, Ming; Cao, Zhuo-Liang

    2004-01-01

    A deterministic teleportation scheme for unknown atomic states is proposed in cavity QED. The Bell state measurement is not needed in the teleportation process, and the success probability can reach 1.0. In addition, the current scheme is insensitive to the cavity decay and thermal field.

  7. Scheme for implementing perfect quantum teleportation with four-qubit entangled states in cavity quantum electrodynamics

    Institute of Scientific and Technical Information of China (English)

    Tang Jing-Wu; Zhao Guan-Xiang; He Xiong-Hui

    2011-01-01

    Recently, Peng et al. [2010 Eur. Phys. J. D 58 403] proposed to teleport an arbitrary two-qubit state with a family of four-qubit entangled states, which simultaneously include the tensor product of two Bell states, linear cluster state and Dicke-class state. This paper proposes to implement their scheme in cavity quantum electrodynamics and then presents a new family of four-qubit entangled state |Ω4)1234. It simultaneously includes all the well-known four-qubit entangled states which can be used to teleport an arbitrary two-qubit state. The distinct advantage of the scheme is that it only needs a single setup to prepare the whole family of four-qubit entangled states, which will be very convenient for experimental realization. After discussing the experimental condition in detail, we show the scheme may be feasible based on present technology in cavity quantum electrodynamics.

  8. Quantum teleportation with independent sources and prior entanglement distribution over a network

    Science.gov (United States)

    Sun, Qi-Chao; Mao, Ya-Li; Chen, Si-Jing; Zhang, Wei; Jiang, Yang-Fan; Zhang, Yan-Bao; Zhang, Wei-Jun; Miki, Shigehito; Yamashita, Taro; Terai, Hirotaka; Jiang, Xiao; Chen, Teng-Yun; You, Li-Xing; Chen, Xian-Feng; Wang, Zhen; Fan, Jing-Yun; Zhang, Qiang; Pan, Jian-Wei

    2016-10-01

    Quantum teleportation faithfully transfers a quantum state between distant nodes in a network, which enables revolutionary information-processing applications. This has motivated a tremendous amount of research activity. However, in the past not a single quantum-teleportation experiment has been realized with independent quantum sources, entanglement distribution prior to the Bell-state measurement (BSM) and feedforward operation simultaneously, even in the laboratory environment. We take the challenge and report the construction of a 30 km optical-fibre-based quantum network distributed over a 12.5 km area. This network is robust against noise in the real world with active stabilization strategies, which allows us to realize quantum teleportation with all the ingredients simultaneously. Both the quantum-state and process-tomography measurements and an independent statistical hypothesis test confirm the quantum nature of the quantum teleportation over this network. Our experiment marks a critical step towards the realization of a global ‘quantum internet’ in the real world.

  9. Reducing Projection Calculation in Quantum Teleportation by Virtue of the IWOP Technique and Schmidt Decomposition of |η〉 State

    Institute of Scientific and Technical Information of China (English)

    FAN Hong-Yi; FAN Yue

    2002-01-01

    By virtue of the technique of integration within an ordered product of operators and the Schmidt decomposition of the entangled state |η〉, we reduce the general projection calculation in the theory of quantum teleportation to a as simple as possible form and present a general formalism for teleportating quantum states of continuous variable.

  10. Quantum teleportation and entanglement. A hybrid approach to optical quantum information procesing

    Energy Technology Data Exchange (ETDEWEB)

    Furusawa, Akira [Tokyo Univ. (Japan). Dept. of Applied Physics; Loock, Peter van [Erlangen-Nuernberg Univ. (Germany). Lehrstuhl fuer Optik

    2011-07-01

    Unique in that it is jointly written by an experimentalist and a theorist, this monograph presents universal quantum computation based on quantum teleportation as an elementary subroutine and multi-party entanglement as a universal resource. Optical approaches to measurement-based quantum computation are also described, including schemes for quantum error correction, with most of the experiments carried out by the authors themselves. Ranging from the theoretical background to the details of the experimental realization, the book describes results and advances in the field, backed by numerous illustrations of the authors' experimental setups. Aimed at researchers, physicists, and graduate and PhD students in physics, theoretical quantum optics, quantum mechanics, and quantum information. (orig.)

  11. Perfect Biparticle Teleportation by Using Multi-particle Quantum Channel with Joint Measurement

    Institute of Scientific and Technical Information of China (English)

    GUO Yan-Qing; NIE Jing; REN Zhong-Zhou; LI Chong; CHEN Yu-Qing; YI Xue-Xi

    2008-01-01

    In this paper, we reinvestigate the faithful quantum teleportation of an arbitrary two-qubit state by a multi-particle channel with multi-particle joint measurements. The relationship between multi-particle quantum channel and the multi-particle joint measurement bases has been found. In addition, we show how to construct the multi-particle joint measurement bases.

  12. Simpler criterion on W state for perfect quantumstate splitting and quantum teleportation

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A simpler criterion is presented to judge whether a W state can be taken as quantum channel forperfectly splitting or teleporting an arbitrary single-qubit state. If the W state is usable,the detailed manipulations in the two quantum information processes are amply shown. Moreover,some relevant discussions are made.

  13. Noise-Resistant Quantum Teleportation, Ansibles, and the No-Projector Theorem

    CERN Document Server

    Hedemann, Samuel R

    2016-01-01

    A method is presented for achieving entanglement-free teleportation of a quantum state subject to any quantum noise. We apply this as a light-speed noise-resistant communicator, but also treat the possibility of a quantum ansible, a device for effectively superluminal communication and quantum broadcasting. The results suggest a "no-projector theorem" analogous to the no-cloning theorem. We then show how to build a pseudo-ansible for connection-free light-speed communication.

  14. Teleportation of Atomic States via Cavity Quantum Electrodynamics

    CERN Document Server

    Guerra, E S

    2004-01-01

    In this article we discuss a scheme of teleportation of atomic states. The experimental realization proposed makes use of cavity Quatum Electrodynamics involving the interaction of Rydberg atoms with a micromaser cavity prepared in a coherent state. We start presenting a scheme to prepare atomic Bell states via the interaction of atoms with a cavity. In our scheme the cavity and some atoms play the role of auxiliary systems used to achieve the teleportation.

  15. Multiparty Quantum Communication Using Multiqubit Entanglement and Teleportation

    Directory of Open Access Journals (Sweden)

    S. Ghose

    2014-01-01

    Full Text Available We propose a 2N qubit entangled channel that can be used to teleport N qubits in a network to a single receiver. We describe the structure of this channel and explicitly demonstrate how the protocol works. The channel can be used to implement a scheme in which all parties have to participate in order for the teleportation to be successful. This can be advantageous in various scenarios and we discuss the potential application of this protocol to voting.

  16. Controlled Teleportation of Multi-qutrit Quantum Information by Swapping Entanglement

    Institute of Scientific and Technical Information of China (English)

    LI Yuan; YANG Jie; ZENG Gui-Hua; LIU Jun

    2008-01-01

    We present a scheme for teleporting multi-qutrit quantum information from a sender to a receiver via the control of many agents in a network. Agents's control parameters are obtained via quantum entanglement swapping. In our scheme, Zhang and Man's QSS protocol [Phys. Rev. A 72 (2005) 022303] based on Bell-state entanglement swapping is generalized to a qutrit case. Our scheme owns the advantage of having higher code capacity and better security than the work [Commun. Theor. Phys. 44 (2005) 847] on controlled teleportation for multi-qubit.

  17. Quantum teleportation and entanglement swapping of electron spins in superconducting hybrid structures

    Energy Technology Data Exchange (ETDEWEB)

    Bubanja, Vladimir, E-mail: vladimir.bubanja@callaghaninnovation.govt.nz

    2015-06-15

    We present schemes for quantum teleportation and entanglement swapping of electronic spin states in hybrid superconductor–normal-metal systems. The proposed schemes employ subgap transport whereby the lowest order processes involve Cooper pair-electron and double Cooper-pair cotunneling in quantum teleportation and entanglement swapping protocols, respectively. The competition between elastic cotunneling and Cooper-pair splitting results in the success probability of 25% in both cases. Described implementations of these protocols are within reach of present-day experimental techniques.

  18. Controlled teleportation

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In this article,we review the recent development of controlled teleportation which can be used for sharing quantum information and has important applications in remote quantum computation.We introduce the principles of a couple of controlled teleportation schemes with maximally entangled quantum channels and those with pure entangled quantum channels (non-maximally entangled states).The schemes based on maximally entangled states have the advantage of having maximal efficiency although there are differences in their implementations in experiment.In the controlled teleportation schemes using non-maximally entangled states as the quantum channels,the receiver can reconstruct the originally unknown state by adding an auxiliary particle and performing a unitary evolution.No matter what the unknown state is (a single qubit state or an m-qudit state),the auxiliary particle required is only a two-level quantum system.

  19. Possibility of Quantum Teleportation and the Reduced Density Matrix

    Institute of Scientific and Technical Information of China (English)

    朱红波; 曾谨言

    2001-01-01

    It is shown that only the maximally entangled two-particle (spin 1/2) states whose one-particle reduced density matrix is p (i) = (1/2)I2 can realize the teleportation of an arbitrary one-particle spin state. Based on this,to teleport an arbitrary k-particle spin state, one must prepare an N-particle entangled state whose k-particle (k < N) reduced density matrix has the structure 2-kI2k (I2k being the 2k × 2k identity matrix). The N-particle Greenberger-Horne-Zeilinger states cannot realize the teleportation of an arbitrary k-particle (N>k≥2) state,except for special states with only two components.

  20. Quantum teleportation of an arbitrary superposition of atomic states

    Institute of Scientific and Technical Information of China (English)

    Chen Qiong; Fang Xi-Ming

    2008-01-01

    This paper proposes a scheme to teleport an arbitrary multi-particle two-level atomic state between two parties or an arbitrary zero- and one-photon entangled state of multi-mode between two high-Q cavities in cavity QED.This scheme is based on the resonant interaction between atom and cavity and does not involve Bell-state measurement.It investigates the fidelity of this scheme and find out the case of this unity fidelity of this teleportation.Considering the practical case of the cavity decay,this paper finds that the condition of the unity fidelity is also valid and obtains the effect of the decay of the cavity on the successful probability of the teleportation.

  1. Probabilistic teleportation of an arbitrary GHZ-class state with a pure entangled two-particle quantum channel and its application in quantum state sharing

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This paper presents a scheme for probabilistic teleportation of an arbitrary GHZ-class state with a pure entangled two-particle quantum channel. The sender Alice first teleports the coefficients of the unknown state to the receiver Bob, and then Bob reconstructs the state with an auxiliary particle and some unitary operations if the teleportation succeeds. This scheme has the advantage of transmitting much less particles for teleporting an arbitrary GHZ-class state than others. Moreover, it discusses the application of this scheme in quantum state sharing.

  2. Two-state teleportation

    CERN Document Server

    Henderson, L; Vedral, V

    1999-01-01

    Quantum teleportation with additional a priori information about the input state achieves higher fidelity than teleportation of a completely unknown state. However, perfect teleportation of two non-orthogonal input states requires the same amount of entanglement as perfect teleportation of an unknown state, namely one ebit. We analyse how well two-state teleportation can be achieved using every degree of pure-state entanglement, and discuss the fidelity of `teleportation' that can be achieved with only classical communication but no shared entanglement. A two-state telecloning scheme is shown to require less entanglement in a certain sense than universal telecloning.

  3. Realistic continuous-variable quantum teleportation with non-Gaussian resources

    CERN Document Server

    Dell'Anno, Fabio; Illuminati, Fabrizio

    2009-01-01

    We present a comprehensive investigation of nonideal continuous-variable quantum teleportation implemented with entangled non-Gaussian resources. We discuss in a unified framework the main decoherence mechanisms, including imperfect Bell measurements and propagation of optical fields in lossy fibers, applying the formalism of the characteristic function. By exploiting appropriate displacement strategies, we compute analytically the success probability of teleportation for input coherent states, and two classes of non-Gaussian entangled resources: Two-mode squeezed Bell-like states (that include as particular cases photon-added and photon-subtracted de-Gaussified states), and two-mode squeezed cat-like states. We discuss the optimization procedure on the free parameters of the non-Gaussian resources at fixed values of the squeezing and of the experimental quantities determining the inefficiencies of the non-ideal protocol. It is found that non-Gaussian resources enhance significantly the efficiency of teleport...

  4. Teleportation of two-atom entangled state in resonant cavity quantum electrodynamics

    Institute of Scientific and Technical Information of China (English)

    Yang Zhen-Biao

    2007-01-01

    An alternative scheme is presented for teleportation of a two-atom entangled state in cavity quantum electrodynamics (QED). It is based on the resonant atom-cavity field interaction. In the scheme, only one cavity is involved, and the number of the atoms needed to be detected is decreased compared with the previous scheme. Since the resonant atom-cavity field interaction greatly reduces the interaction time, the decoherence effect can be effectively suppressed during the teleportation process. The experimental feasibility of the scheme is discussed. The scheme can easily be generalized to the teleportation of N-atom Greeninger-Horne-Zeilinger (GHZ) entangled states. The number of atoms needed to be detected does not increase as the number of the atoms in the GHZ state increases.

  5. Improvement of a quantum broadcasting multiple blind signature scheme based on quantum teleportation

    Science.gov (United States)

    Zhang, Wei; Qiu, Daowen; Zou, Xiangfu

    2016-06-01

    Recently, a broadcasting multiple blind signature scheme based on quantum teleportation has been proposed for the first time. It is claimed to have unconditional security and properties of quantum multiple signature and quantum blind signature. In this paper, we analyze the security of the protocol and show that each signatory can learn the signed message by a single-particle measurement and the signed message can be modified at random by any attacker according to the scheme. Furthermore, there are some participant attacks and external attacks existing in the scheme. Finally, we present an improved scheme and show that it can resist all of the mentioned attacks. Additionally, the secret keys can be used again and again, making it more efficient and practical.

  6. Quantum Teleportation Schemes of an N-Particle State via Three-Particle General W States

    Institute of Scientific and Technical Information of China (English)

    JI Ying-Hua; XIU Xiao-Ming; DONG Li; GAO Ya-Jun; CHI Feng

    2008-01-01

    Two schemes of teleporting an N-particle arbitrary and unknown state are proposed when N groups of three-particle general W states are utilized as quantum channels. In the first scheme, the quantum channels are shared by the sender and the recipient. After the sender's Bell-state measurements on his (her) particles, the recipient carries out unitary transformations on his (her) particles. And then, the recipient performs computational basis measurements to realize the teleportation. The recipient can recover the state on either of particle sequences with the equal maximal probability of successful teleportation if he (she) performs appropriate unitary transformations. In the second scheme, the quantum channels are shared by the sender, the recipient and the third ones. After the sender's Be11-state measurements and the third ones' computational basis measurements if they agree to cooperate, the recipient will introduce auxiliary particles and carry out appropriate unitary transformations. Finally, the recipient performs computational basis measurements to fulfill the teleportation. The second scheme can be realized if and only if the third ones agree to cooperate with the recipient.

  7. Quantum circuits for realizing deterministic and exact teleportation via two partially entangled pairs of particles

    Institute of Scientific and Technical Information of China (English)

    Li Wen-Dong; Zhang Jian-Li; Gu Yong-Jian

    2006-01-01

    Deterministic and exact teleportation can be achieved via two partially entangled pairs of particles[Gu Y J 2006 Opt.Comm.259 385].The key point of the protocol is a generalized measurement described by a positive operator valued measure, which can be realized by performing a unitary operation in the extended space and a conventional Von Neumann orthogonal measurement.By decomposing the evolution process from the initial state to the final state, we construct the quantum circuits for realizing the unitary operation with quantum Toffoli gates, and thus provide a physical means to realize the teleportation.Our method for constructing quantum circuits differs from the usual methods based on decomposition of unitary matrices, and is convenient for a large class of quantum processes involving generalized measurements.

  8. Experimental realization of quantum teleportation from a photon to the vibration modes of a millimeter-sized diamond

    Science.gov (United States)

    Huang, Yuanyuan; Hou, Panyu; Yuan, Xinxing; Chang, Xiuying; Zu, Chong; He, Li; Duan, Luming; CenterQuantum Information, IIIS, Tsinghua University, Beijing 100084, PR China Team; Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA Team

    2016-05-01

    Quantum teleportation is of great importance to various quantum technologies, and has been realized between light beams, trapped atoms, superconducting qubits, and defect spins in solids. Here we report an experimental demonstration of quantum teleportation from light beams to vibrational states of a macroscopic diamond under ambient conditions. In our experiment, the ultrafast laser technology provides the key tool for fast processing and detection of quantum states within its short life time in macroscopic objects consisting of many strongly interacting atoms that are coupled to the environment, and finally we demonstrate an average teleportation fidelity (90 . 6 +/- 1 . 0) % , clearly exceeding the classical limit of 2/3. Quantum control of the optomechanical coupling may provide efficient ways for realization of transduction of quantum signals, processing of quantum information, and sensing of small mechanical vibrations. Center for Quantum Information, IIIS, Tsinghua University, Beijing 100084, PR China.

  9. High teleportation rates using cold-atom-ensemble-based quantum repeaters with Rydberg blockade

    Science.gov (United States)

    Solmeyer, Neal; Li, Xiao; Quraishi, Qudsia

    2016-04-01

    We present a simplified version of a repeater protocol in a cold neutral-atom ensemble with Rydberg excitations optimized for two-node entanglement generation and describe a protocol for quantum teleportation. Our proposal draws from previous proposals [B. Zhao et al., Phys. Rev. A 81, 052329 (2010), 10.1103/PhysRevA.81.052329; Y. Han et al., Phys. Rev. A 81, 052311 (2010), 10.1103/PhysRevA.81.052311] that described efficient and robust protocols for long-distance entanglement with many nodes. Using realistic experimental values, we predict an entanglement generation rate of ˜25 Hz and a teleportation rate of ˜5 Hz . Our predicted rates match the current state-of-the-art experiments for entanglement generation and teleportation between quantum memories. With improved efficiencies we predict entanglement generation and teleportation rates of ˜7.8 and ˜3.6 kHz, respectively, representing a two-order-of-magnitude improvement over the currently realized values. Cold-atom ensembles with Rydberg excitations are promising candidates for repeater nodes because collective effects in the ensemble can be used to deterministically generate a long-lived ground-state memory which may be efficiently mapped onto a directionally emitted single photon.

  10. Disentangling Nonlocality and Teleportation

    CERN Document Server

    Hardy, L

    1999-01-01

    Quantum entanglement can be used to demonstrate nonlocality and to teleport a quantum state from one place to another. The fact that entanglement can be used to do both these things has led people to believe that teleportation is a nonlocal effect. In this paper it is shown that teleportation is conceptually independent of nonlocality. This is done by constructing a toy local theory in which cloning is not possible (without a no-cloning theory teleportation makes limited sense) but teleportation is. Teleportation in this local theory is achieved in an analogous way to the way it is done with quantum theory. This work provides some insight into what type of process teleportation is.

  11. Multi-agent controlled teleportation of multi-qubit quantum information via two-step protocol

    Institute of Scientific and Technical Information of China (English)

    Yang Jie

    2005-01-01

    Utilizing both the general quantum teleportation and the two-step protocol, a new method is presented by which multi-qubit quantum information can be teleported in a much easier way from a sender Alice to a receiver Bob via the control of many agents in a network than by Yang et al's method. In this method, only all the agents collaborate with Bob can the unknown states in Alice's qubits be fully reconstructed in Bob's qubits. Comparisons between the method and Yang et al's method are made. Results show that, in this method, the preparation difficulty of initial states and the identification difficulty of entangled states are considerably reduced, new method is more feasible in technique, and Hadamard operations are not needed at all.

  12. Effect of relativistic acceleration on continuous variable quantum teleportation and dense coding

    OpenAIRE

    Grochowski, Piotr T.; Rajchel, Grzegorz; Kiałka, Filip; Dragan, Andrzej

    2017-01-01

    We investigate how relativistic acceleration of the observers can affect the performance of the quantum teleportation and dense coding for continuous variable states of localized wavepackets. Such protocols are typically optimized for symmetric resources prepared in an inertial frame of reference. A mismatch of the sender and the receiver's accelerations can introduce asymmetry to the shared entanglement, which has an effect on the efficiency of the protocol that goes beyond entanglement degr...

  13. Research on an E-mail Encryption Protocol Based on Quantum Teleportation

    Science.gov (United States)

    Shufen, Xiao; Yumin, Dong; Hongyang, Ma; Libo, Chen

    2016-07-01

    With the rapid development of information technology (IT), E-mail has become an important communication tool between human beings. Meanwhile, E-mail safety becomes increasingly important because of its universal applications. In order to overcome shortages of classical E-mail encryption, an E-mail encryption protocol based on quantum teleportation was proposed. It makes quantum encryption of E-mails during sending and receiving processes by taking advantages of entanglement and nonclonability of quantum, thus ensuring safety and reliability of E-mail transmission.

  14. Research on an E-mail Encryption Protocol Based on Quantum Teleportation

    Science.gov (United States)

    Shufen, Xiao; Yumin, Dong; Hongyang, Ma; Libo, Chen

    2016-11-01

    With the rapid development of information technology (IT), E-mail has become an important communication tool between human beings. Meanwhile, E-mail safety becomes increasingly important because of its universal applications. In order to overcome shortages of classical E-mail encryption, an E-mail encryption protocol based on quantum teleportation was proposed. It makes quantum encryption of E-mails during sending and receiving processes by taking advantages of entanglement and nonclonability of quantum, thus ensuring safety and reliability of E-mail transmission.

  15. Quantum teleportation and entanglement swapping of matter qubits with multiphoton signals

    Energy Technology Data Exchange (ETDEWEB)

    Torres, Juan Mauricio [Institut fuer Angewandte Physik, Technische Universitaet Darmstadt, D-64289 Germany (Germany); Departamento de Investigacion en Fisica, Universidad de Sonora, Hermosillo (Mexico); Bernad, Jozsef Zsolt; Alber, Gernot [Institut fuer Angewandte Physik, Technische Universitaet Darmstadt, D-64289 Germany (Germany)

    2014-07-01

    We introduce a probabilistic Bell measurement of atomic qubits based on two consecutive photonic field measurements of two single mode cavities with which the atoms interact in two separate stages. To this end, we solve the two-atoms Tavis-Cummings model and exploit the property that the antisymmetric Bell state is insensitive to the interaction with the field. We consider implementations for quantum teleportation and for entanglement swapping protocols both of which can be achieved with 25% success probability and with unit fidelity. We emphasize possible applications for hybrid quantum repeaters where the aforementioned quantum protocols play an essential role.

  16. Deterministic quantum teleportation with feed-forward in a solid state system.

    Science.gov (United States)

    Steffen, L; Salathe, Y; Oppliger, M; Kurpiers, P; Baur, M; Lang, C; Eichler, C; Puebla-Hellmann, G; Fedorov, A; Wallraff, A

    2013-08-15

    Engineered macroscopic quantum systems based on superconducting electronic circuits are attractive for experimentally exploring diverse questions in quantum information science. At the current state of the art, quantum bits (qubits) are fabricated, initialized, controlled, read out and coupled to each other in simple circuits. This enables the realization of basic logic gates, the creation of complex entangled states and the demonstration of algorithms or error correction. Using different variants of low-noise parametric amplifiers, dispersive quantum non-demolition single-shot readout of single-qubit states with high fidelity has enabled continuous and discrete feedback control of single qubits. Here we realize full deterministic quantum teleportation with feed-forward in a chip-based superconducting circuit architecture. We use a set of two parametric amplifiers for both joint two-qubit and individual qubit single-shot readout, combined with flexible real-time digital electronics. Our device uses a crossed quantum bus technology that allows us to create complex networks with arbitrary connecting topology in a planar architecture. The deterministic teleportation process succeeds with order unit probability for any input state, as we prepare maximally entangled two-qubit states as a resource and distinguish all Bell states in a single two-qubit measurement with high efficiency and high fidelity. We teleport quantum states between two macroscopic systems separated by 6 mm at a rate of 10(4) s(-1), exceeding other reported implementations. The low transmission loss of superconducting waveguides is likely to enable the range of this and other schemes to be extended to significantly larger distances, enabling tests of non-locality and the realization of elements for quantum communication at microwave frequencies. The demonstrated feed-forward may also find application in error correction schemes.

  17. Several teleportation schemes of an arbitrary unknown multi-particle state via different quantum channels

    Institute of Scientific and Technical Information of China (English)

    Peng Jia-Yin; Mo Zhi-Wen

    2013-01-01

    We first provide four new schemes for two-party quantum teleportation of an arbitrary unknown multi-particle state by using three-,four-,and five-particle states as the quantum channel,respectively.The successful probability and fidelity of the four schemes reach 1.In the first two schemes,the receiver can only apply one of the unitary transformations to reconstruct the original state,making it easier for these two schemes to be directly realized.In the third and fourth schemes,the sender can preform Bell-state measurements instead of multipartite entanglement measurements of the existing similar schemes,which makes real experiments more suitable.It is found that the last three schemes may become tripartite controlled teleportation schemes of teleporting an arbitrary multi-particle state after a simple modification.Finally,we present a new scheme for three-party sharing an arbitrary unknown multi-particle state.In this scheme,the sender first shares three three-particle GHZ states with two agents.After setting up the secure quantum channel,an arbitrary unknown multi-particle state can be perfectly teleported if the sender performs three Bell-state measurements,and either of two receivers operates an appropriate unitary transformation to obtain the original state with the help of other receiver's three single-particle measurements.The successful probability and fidelity of this scheme also reach 1.It is demonstrated that this scheme can be generalized easily to the case of sharing an arbitrary unknown multi-particle state among several agents.

  18. Quantum superposition, entanglement, and state teleportation of a microorganism on an electromechanical oscillator

    CERN Document Server

    Li, Tongcang

    2016-01-01

    Schr\\"odinger's thought experiment to prepare a cat in a superposition of both alive and dead states reveals profound consequences of quantum mechanics and has attracted enormous interests. Here we propose a straightforward method to create quantum superposition states of a living microorganism by putting a small bacterium on top of an electromechanical oscillator. Our proposal is based on recent developments that the center-of-mass oscillation of a 15-$\\mu$m-diameter aluminium membrane has been cooled to its quantum ground state [Nature 475, 359 (2011)], and entangled with a microwave field [Science, 342, 710 (2013)]. A microorganism with a mass much smaller than the mass of the electromechanical membrane will not significantly affect the quality factor of the membrane and can be cooled to the quantum ground state together with the membrane. Quantum superposition and teleportation of its center-of-mass motion state can be realized with the help of superconducting microwave circuits. More importantly, the int...

  19. Teleportation Dream or Reality?

    CERN Document Server

    Vaidman, L

    1999-01-01

    Since its discovery in 1993, we witness an intensive theoretical and experimental effort centered on teleportation. Very recently it was claimed in the press that ``quantum teleportation has been achieved in the laboratory'' (T. Sudbery, Nature, 390, p. 551). Here, I briefly review this research focusing on the connection to nonlocal measurements, and question Sudbery's statement. A philosophical inquiry about the paradoxical meaning of teleportation in the framework of the many-worlds interpretation is added.

  20. Teleportation: Dream or reality?

    Science.gov (United States)

    Vaidman, Lev

    1999-03-01

    Since its discovery in 1993, we witness an intensive theoretical and experimental effort centered on teleportation. Very recently it was claimed in the press that "quantum teleportation has been achieved in the laboratory" (T. Sudbery, Nature 390, 551). Here, I briefly review this research focusing on the connection to nonlocal measurements, and question Sudbery's statement. A philosophical inquiry about the paradoxical meaning of teleportation in the framework of the many-worlds interpretation is added.

  1. Generating multi-photon W-like states for perfect quantum teleportation and superdense coding

    Science.gov (United States)

    Li, Ke; Kong, Fan-Zhen; Yang, Ming; Ozaydin, Fatih; Yang, Qing; Cao, Zhuo-Liang

    2016-08-01

    An interesting aspect of multipartite entanglement is that for perfect teleportation and superdense coding, not the maximally entangled W states but a special class of non-maximally entangled W-like states are required. Therefore, efficient preparation of such W-like states is of great importance in quantum communications, which has not been studied as much as the preparation of W states. In this paper, we propose a simple optical scheme for efficient preparation of large-scale polarization-based entangled W-like states by fusing two W-like states or expanding a W-like state with an ancilla photon. Our scheme can also generate large-scale W states by fusing or expanding W or even W-like states. The cost analysis shows that in generating large-scale W states, the fusion mechanism achieves a higher efficiency with non-maximally entangled W-like states than maximally entangled W states. Our scheme can also start fusion or expansion with Bell states, and it is composed of a polarization-dependent beam splitter, two polarizing beam splitters and photon detectors. Requiring no ancilla photon or controlled gate to operate, our scheme can be realized with the current photonics technology and we believe it enable advances in quantum teleportation and superdense coding in multipartite settings.

  2. The Grammar of Teleportation

    CERN Document Server

    Timpson, C G

    2005-01-01

    Whilst a straightforward consequence of the formalism of non-relativistic quantum mechanics, the phenomenon of quantum teleportation has given rise to considerable puzzlement. In this paper, the teleportation protocol is reviewed and these puzzles dispelled. It is suggested that they arise from two primary sources: 1) the familiar error of hypostatizing an abstract noun (in this case, `information') and 2) failure to differentiate interpretation dependent from interpretation independent features of quantum mechanics. A subsidiary source of error, the simulation fallacy, is also identified. The resolution presented of the puzzles of teleportation illustrates the benefits of paying due attention to the logical status of `information' as an abstract noun.

  3. Efficient scheme for hybrid teleportation via entangled coherent states in circuit quantum electrodynamics.

    Science.gov (United States)

    Joo, Jaewoo; Ginossar, Eran

    2016-06-01

    We propose a deterministic scheme for teleporting an unknown qubit state through continuous-variable entangled states in superconducting circuits. The qubit is a superconducting two-level system and the bipartite quantum channel is a microwave photonic entangled coherent state between two cavities. A Bell-type measurement performed on the hybrid state of solid and photonic states transfers a discrete-variable unknown electronic state to a continuous-variable photonic cat state in a cavity mode. In order to facilitate the implementation of such complex protocols we propose a design for reducing the self-Kerr nonlinearity in the cavity. The teleporation scheme enables quantum information processing operations with circuit-QED based on entangled coherent states. These include state verification and single-qubit operations with entangled coherent states. These are shown to be experimentally feasible with the state of the art superconducting circuits.

  4. Efficient scheme for hybrid teleportation via entangled coherent states in circuit quantum electrodynamics

    Science.gov (United States)

    Joo, Jaewoo; Ginossar, Eran

    2016-06-01

    We propose a deterministic scheme for teleporting an unknown qubit state through continuous-variable entangled states in superconducting circuits. The qubit is a superconducting two-level system and the bipartite quantum channel is a microwave photonic entangled coherent state between two cavities. A Bell-type measurement performed on the hybrid state of solid and photonic states transfers a discrete-variable unknown electronic state to a continuous-variable photonic cat state in a cavity mode. In order to facilitate the implementation of such complex protocols we propose a design for reducing the self-Kerr nonlinearity in the cavity. The teleporation scheme enables quantum information processing operations with circuit-QED based on entangled coherent states. These include state verification and single-qubit operations with entangled coherent states. These are shown to be experimentally feasible with the state of the art superconducting circuits.

  5. Teleporting a quantum controlled-Not with one target/two targets gate using two partially entangled states

    Institute of Scientific and Technical Information of China (English)

    Chen Li-Bing; Jin Rui-Bo; Lu Hong

    2009-01-01

    This paper considers the teleportation of quantum controlled-Not (CNOT) gate by using partially entangled states. Different from the known probability schemes, it presents a method for teleporting a CNOT gate with unit fidelity and unit probability by using two partially entangled pairs as quantum channel. The method is applicable to any two partially entangled pairs satisfying the condition that their smaller Schmidt coefficients μ and ν are (2μ + 2ν - 2μν - 1)≥0. In this scheme, the sender's local generalized measurement described by a positive operator valued measurement (POVM) lies at the heart. It constructs the required POVM. It also puts forward a scheme for teleporting a CNOT with two targets gate with unit fidelity by using same quantum channel. With assistance of local operations and classical communications, three spatially separated users are able to complete the teleportation of a CNOT with two targets gate with probability of (2μ + 2ν - 1). With a proper value of μ and ν, the probability could reach nearly 1.

  6. High-fidelity teleportation of continuous-variable quantum States using delocalized single photons

    DEFF Research Database (Denmark)

    Andersen, Ulrik L; Ralph, Timothy C

    2013-01-01

    states as in traditional teleportation but on an ensemble of single photon entangled states. We characterize the teleportation scheme with coherent states, mesoscopic superposition states, and two-mode squeezed states and we find several situations in which near-unity teleportation fidelity can...

  7. Multiple teleportation via partially entangled GHZ state

    Science.gov (United States)

    Xiong, Pei-Ying; Yu, Xu-Tao; Zhan, Hai-Tao; Zhang, Zai-Chen

    2016-08-01

    Quantum teleportation is important for quantum communication. We propose a protocol that uses a partially entangled Greenberger-Horne-Zeilinger (GHZ) state for single hop teleportation. Quantum teleportation will succeed if the sender makes a Bell state measurement, and the receiver performs the Hadamard gate operation, applies appropriate Pauli operators, introduces an auxiliary particle, and applies the corresponding unitary matrix to recover the transmitted state.We also present a protocol to realize multiple teleportation of partially entangled GHZ state without an auxiliary particle. We show that the success probability of the teleportation is always 0 when the number of teleportations is odd. In order to improve the success probability of a multihop, we introduce the method used in our single hop teleportation, thus proposing a multiple teleportation protocol using auxiliary particles and a unitary matrix. The final success probability is shown to be improved significantly for the method without auxiliary particles for both an odd or even number of teleportations.

  8. Simplified Scheme for Teleportation of a Multipartite Quantum State Using a Single Entangled Pair

    Institute of Scientific and Technical Information of China (English)

    YAN Li-Hua; GAO Yun-Feng

    2009-01-01

    A simple scheme for teleporting an unknown M-qubit cat-like state is proposed.The steps of this scheme can be summarized simpIy: disentangle-teleport-reconstruct entanglement.If proper unitary operations and measurements from senders are given, the teleportation of an unknown M-qubit cat-like state can be converted into single qubit teleportation.In the meantime, the receiver should also carry out right unitary operations with the introduction of appropriate ancillary qubits to confirm the successful teleportation of the demanded entangled state.The present scheme can be generalized to teleport an unknown M-quNit state, i.e., an M-quNit state can be teleported by a single quNit entangled pair.

  9. Squeezing the limit: quantum benchmarks for the teleportation and storage of squeezed states

    Energy Technology Data Exchange (ETDEWEB)

    Owari, M; Plenio, M B [Institute for Mathematical Sciences, 53 Prince' s Gate, Imperial College London, London SW7 2PG (United Kingdom); Polzik, E S; Wolf, M M [Niels Bohr Institute, Copenhagen University, Blegdamsvej 17, DK-2100 Copenhagen Oe (Denmark); Serafini, A [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom)], E-mail: m.owari@imperial.ac.uk

    2008-11-15

    We derive fidelity benchmarks for the quantum storage and teleportation of squeezed states of continuous variable systems, for input ensembles where the degree of squeezing s is fixed, no information about its orientation in phase space is given, and the distribution of phase-space displacements is a Gaussian. In the limit where the latter becomes flat, we prove analytically that the maximal classical achievable fidelity (which is 1/2 without squeezing, for s=1) is given by {radical}s/(1+s), vanishing when the degree of squeezing diverges. For mixed states, as well as for general distributions of displacements, we reduce the determination of the benchmarks to the solution of a finite-dimensional semidefinite program, which yields accurate, certifiable bounds thanks to a rigorous analysis of the truncation error. This approach may be easily adapted to more general ensembles of input states.

  10. Teleportation the impossible leap

    CERN Document Server

    Darling, David

    2005-01-01

    An authoritative, entertaining examination of the ultimate thrill ride Until recently the stuff of sci-fi fiction and Star Trek reruns, teleportation has become a reality-for subatomic particles at least. In this eye-opening book, science author David Darling follows the remarkable evolution of teleportation, visiting the key labs that have cradled this cutting-edge science and relating the all-too-human stories behind its birth. He ties in the fast emerging fields of cryptography and quantum computing, tackles some thorny philosophical questions (for instance, can a soul be teleported?)

  11. Teleportation via decay

    Indian Academy of Sciences (India)

    S Bose; P L Knight; M B Plenio; V Vedral

    2001-02-01

    We present a rare example of a decay mechanism playing a constructive role in quantum information processing. We show how the state of an atom trapped in a cavity can be teleported to a second atom trapped in a distant cavity by the joint detection of photon leakage from the cavities. The scheme, which is probabilistic, requires only a single three level atom in a cavity. We also show how this scheme can be modified to a teleportation with insurance.

  12. Defending Continuous Variable Teleportation: Why a laser is a clock, not a quantum channel

    CERN Document Server

    Wiseman, H M

    2004-01-01

    It has been argued [T. Rudolph and B.C. Sanders, Phys. Rev. Lett. {\\bf 87}, 077903 (2001)] that continuous-variable quantum teleportation at optical frequencies has not been achieved because the source used (a laser) was not `truly coherent'. Van Enk, and Fuchs [Phys. Rev. Lett, {\\bf 88}, 027902 (2002)], while arguing against Rudolph and Sanders, also accept that an `absolute phase' is achievable, even if it has not been achieved yet. I will argue to the contrary that `true coherence' or `absolute phase' is always illusory, as the concept of absolute time (at least for frequencies beyond direct human experience) is meaningless. All we can ever do is to use an agreed time standard. In this context, a laser beam is fundamentally as good a `clock' as any other. I explain in detail why this claim is true, and defend my argument against various objections. In the process I discuss super-selection rules, quantum channels, and the ultimate limits to the performance of a laser as a clock. For this last topic I use so...

  13. Scheme for Teleportation of a Multipartite Quantum State by Using a Single Entangled Pair as Quantum Channel

    Institute of Scientific and Technical Information of China (English)

    WANG Xin-Wen; WANG Zhi-Yong; XIA Li-Xin

    2007-01-01

    We present a theoretical scheme for perfect teleportation of an unknown multipartite two-level state by a single EPR (Einstein-Podolsky-Rosen) pair,and then generalize it to multilevel,i.e.,an N-quNit state can be teleported by a single quNit entangled pair,with additional local unitary operations.The feature of the scheme is that teleporting a multipartite state with a reduced amount of entanglement costs less classical bits.

  14. The decoherence of quantum entanglement and teleportation in Bell-diagonal states

    Institute of Scientific and Technical Information of China (English)

    QIN Meng; LI Yan-Biao; WANG Xiao; BAI Zhong

    2012-01-01

    We study the dynamics of entanglement and teleportation in Bell-diagonal states. Using the concepts of concurrence and fidelity,the analytical expressions of the entanglement,the output entanglement and the average fidelity with decoherence are obtained for this model.We discover a class of initial states in which the output entanglement and the average fidelity are destroyed by decoherence. The quality of teleportation depends on the system parameters and time.

  15. Multiparticle Generalization of Teleportation

    Institute of Scientific and Technical Information of China (English)

    YANG Chui-Ping; GUO Guang-Can

    2000-01-01

    A scheme for teleporting an unknown quantum state of many particles is proposed. The scheme operates es sentially by prearranging the sharing of an Einstein-Podolsky-Rosen-correlated pair of particles every time. We show that after performing a series of Bell-state measurements and single-particle unitary transformations, the unknown state of many particles, which was destroyed at one place, can be reconstructed at another place. Our scheme is actually obtained by generalizing an earlier scheme of Bennett et al. [Phys. Rev. Lett. 70 (1993) 1895; 76 (1996) 722] known as quantum teleportation to the multiparticle case.

  16. Using less Quantum Resource for Probabilistic Controlled Teleportation of a Triplet W State

    Directory of Open Access Journals (Sweden)

    Xian-Ming Wang

    2012-10-01

    Full Text Available In a recent paper [CHIN. PHYS. LETT. Vol.26,No.7(2009070306 ], DONG et al. proposed a scheme for probabilistic controlled teleportation of a triplet W state using combined non-maximally entangled channel of two Einstein–Podolsky–Rosen (EPR states and one Greenberger–Horne–Zeilinger (GHZ state. In this paper ,only using one Einstein–Podolsky–Rosen (EPR state and one Greenberger–Horne–Zeilinger (GHZ state,the scheme for probabilistic controlled teleportation of a triplet W state is presented. Furthermore, Comparing with the widely used Bell-State measurement, Alice performs orthogonal complete basis measurement in the current work. Then Bob can faithfully reconstruct the original state by performing relevant unitary transformations. The total probability of successful teleportation is only dependent on channel coefficients of EPR state and GHZ state.  

  17. Probabilistic Teleportation of a Three-Particle State

    Institute of Scientific and Technical Information of China (English)

    FANG Jian-Xing; ZHU Shi-Qun; ZHANG Rong; CHEN Xian-Feng

    2003-01-01

    A scheme for teleporting a three-particle state is proposed when three pairs of entangled particles are used as quantum channels. Quantum teleportation can be successfully realized with a certain probability if the receiver adopts an appropriate unitary-reduction strategy. The probability of successful teleportation is determined by the smaller coetficients of the three entangled pairs.

  18. Probabilistic Teleportation of a Three-Particle State

    Institute of Scientific and Technical Information of China (English)

    FANGJian-Xing; ZHUShi-Qun; ZHANGRong; CHENXian-Feng

    2003-01-01

    A scheme for teleporting a three-particle state is proposed when three pairs of entangled particles are used as quantum channels. Quantum teleportation can be successfully realized with a certain probability if the receiver adopts an appropriate unitary-reduction strategy. The probability of successful teleportation is determined by the smaller coefficients of the three entangled pairs.

  19. Continuous variable teleportation of single photon states (Proceedings version)

    OpenAIRE

    Ide, Toshiki; Hofmann, Holger F.; Kobayashi, Takayoshi; Furusawa, Akira

    2001-01-01

    We investigate the changes to a single photon state caused by the non-maximal entanglement in continuous variable quantum teleportation. It is shown that the teleportation measurement introduces field coherence in the output.

  20. Star-Trek Teleportation: A Possibility?

    CERN Document Server

    Kho, Kiang Wei

    2011-01-01

    This paper describes a scheme, through which the quantum information as well as the structural information of a time-reversal invariant system can be teleported over a distance. I show that my teleportation scheme can be viewed as a form of reversible purification process by repeated interactions with an auxiliary quantum system.

  1. Pulsed energy-time entangled twin-photon source for quantum communication

    CERN Document Server

    Brendel, J; Tittel, W; Zbinden, H

    1999-01-01

    A pulsed source of energy-time entangled photon pairs pumped by a standard laser diode is proposed and demonstrated. The basic states can be distinguished by their time of arrival. This greatly simplifies the realization of 2-photon quantum cryptography, Bell state analyzers, quantum teleportation, dense coding, entanglement swapping, GHZ-states sources, etc. Moreover the entanglement is well protected during photon propagation in telecom optical fibers, opening the door to few-photon applications of quantum communication over long distances.

  2. Teleportation of a three-particle entangled W state

    Institute of Scientific and Technical Information of China (English)

    郑亦庄; 顾永建; 郭光灿

    2002-01-01

    We have investigated the problem of teleporting a three-particle entangled W state and we propose a scheme based on entanglement swapping to complete the teleportation. We also put forward a scheme for the teleportation of a general W state by using nonmaximally entangled quantum channels. The probability of success of the latter scheme is obtained.

  3. Teleportation of Atomic States in a Vacuum-Induced Environment

    Institute of Scientific and Technical Information of China (English)

    LIU Jin; SHAO Bin; XIANG Shao-Hua; ZOU Jian

    2009-01-01

    We present a scheme for teleporting atomic state through a dissipative quantum channel induced by spontaneous emission and investigate the destructive effect of the atomic decay on the success probability and the fidelity of teleportation associated to different channels. It is found that there exists an optimal channel to realize faithful teleportation.

  4. Comment on "Fractional quantum mechanics" and "Fractional Schroedinger equation"

    CERN Document Server

    Wei, Yuchuan

    2016-01-01

    In this comment, we point out some shortcomings in two papers "Fractional quantum mechanics" [Phys. Rev. E 62, 3135 (2000)] and "Fractional Schroedinger equation" [Phys. Rev. E 66, 056108 (2002)]. We prove that the fractional uncertainty relation does not hold generally. The probability continuity equation in fractional quantum mechanics has a missing source term, which leads to particle teleportation, i.e., a particle can teleport from one place to another. Since the relativistic kinetic energy can be viewed as an approximate realization of the fractional kinetic energy, the particle teleportation should be an observable relativistic effect in quantum mechanics. With the help of this concept, superconductivity could be viewed as the teleportation of electrons from one side of a superconductor to another and superfluidity could be viewed as the teleportation of helium atoms from one end of a capillary tube to the other. We also point out how to teleport a particle to a destination.

  5. Long distance atomic teleportation with as good success as desired

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, Manoj K., E-mail: manoj.qit@gmail.com [Physics Department, University of Allahabad (India); Space Applications Centre, Indian Space Research Organization (ISRO), Ahmedabad (India); Prakash, Hari [Physics Department, University of Allahabad (India); Indian Institute of Information Technology, Allahabad (India)

    2015-09-15

    Long distance atomic teleportation (LDAT) is of prime importance in long distance quantum communication. Scheme proposed by Bose et al. (1999) in principle enables us to have LDAT using cavity decay. However it gives message state dependent fidelity and success rate. Here, using interaction of entangled coherent states with atom–cavity systems and a two-step measurement, we show how, LDAT can be achieved with unit fidelity and as good success as desired under ideal conditions. The scheme is unique in that, the first measurement predicts success or failure. If success is predicted then second measurement gives perfect teleportation. If failure is predicted the message-qubit remains conserved therefore a second attempt may be started. We found that even in presence of decoherence due to dissipation of energy our scheme gives message state independent success rate and almost perfect teleportation in single attempt with mean fidelity of teleportation equal to 0.9 at long distances. However if first attempt fails, unlike ideal case where message-qubit remains conserved with unit fidelity, in presence of decoherence the message-qubit remains conserved to some degree, therefore mean fidelity of teleportation can be increased beyond 0.9 by repeating the process.

  6. Qudit-Teleportation for photons with linear optics

    CSIR Research Space (South Africa)

    Goyal, SK

    2014-04-01

    Full Text Available Quantum teleportation, the transfer of the state of one quantum system to another without direct interaction between both systems, is an important way to transmit information encoded in quantum states and to generate quantum correlations...

  7. Teleportation of Nonclassical Wave Packets of light

    CERN Document Server

    Lee, Noriyuki; Takeno, Yuishi; Takeda, Shuntaro; Webb, James; Huntington, Elanor; Furusawa, Akira

    2012-01-01

    We report on the experimental quantum teleportation of strongly nonclassical wave packets of light. To perform this full quantum operation while preserving and retrieving the fragile non-classicality of the input state, we have developed a broadband, zero-dispersion teleportation apparatus that works in conjunction with time-resolved state preparation equipment. Our approach brings within experimental reach a whole new set of hybrid protocols involving discrete- and continuous-variable techniques in quantum information processing for optical sciences.

  8. Feasible Teleportation Schemes with Five-Atom Entangled State

    Institute of Scientific and Technical Information of China (English)

    XUE Zheng-Yuan; YI You-Min; CAO Zhuo-Liang

    2006-01-01

    Teleportation schemes with a five-atom entangled state are investigated. In the teleportation scheme Bell state measurements (BSMs) are difficult for physical realization, so we investigate another strategy using separate measurements instead of BSM based on cavity quantum electrodynamics techniques. The scheme of two-atom entangled state teleportation is a controlled and probabilistic one. For the teleportation of the three-atom entangled state, the scheme is a probabilistic one. The fidelity and the probability of the successful teleportation are also obtained.

  9. Teleportation of Multi-qudit Entangled States

    Institute of Scientific and Technical Information of China (English)

    ZHAN Xiao-Gui; LI Hong-Mei; ZENG Hao-Sheng

    2006-01-01

    @@ We propose a method to realize the teleportation of an unknown entangled state that consists of many qudits through a partially entangled-qudit quantum channel with the help of 2 log2 d-bit classical communication. The operations used in the teleportation process include a generalized Bell-state measurement and a series of singlequdit π-measurements performed by Alice, a series of generalized qudit-Pauli gates and two-level unitary gates,as well as a qubit measurement performed by Bob. For a maximally entangled quantum channel, the successful probability of the teleportation becomes unit.

  10. Teleport Generation 3 (Teleport Gen 3)

    Science.gov (United States)

    2016-03-01

    8596 DSN Fax: Date Assigned: September 4, 2014 Program Information Program Name Teleport Generation 3 (Teleport Gen 3) DoD Component DoD The...2015 Approved APB Component Acquisition Executive (CAE) Approved Acquisition Program Baseline (APB) dated June 15, 2015 Teleport Gen 3 2016 MAR...System Network (DISN). The DoD Teleport upgrades selected sites from the Standardized Tactical Entry Point (STEP) program, which only provides reach

  11. Teleporting independent qubits through a 97 km free-space channel

    CERN Document Server

    Yin, Juan; Ren, Ji-Gang; Cao, Yuan; Yong, Hai-Lin; Wu, Yu-Ping; Liu, Chang; Liao, Sheng-Kai; Jiang, Yan; Cai, Xin-Dong; Xu, Ping; Pan, Ge-Sheng; Wang, Jian-Yu; Chen, Yu-Ao; Peng, Cheng-Zhi; Pan, Jian-Wei

    2012-01-01

    With the help of quantum entanglement, quantum communication can be achieved between arbitrarily distant places without passing through intermediate locations by quantum teleportation. In the laboratory, quantum teleportation has been demonstrated over short distance by photonic and atomic qubits. Using fiber links, quantum teleportation has been achieved over kilometer distances. Long distance quantum teleportation is of particular interest and has been one of the holy grails of practical quantum communication. Most recently, quantum teleportation over 16 km free-space link was demonstrated. However, a major restriction in this experiment is that the unknown quantum state cannot directly come from outside. Here, based on an ultra-bright multi-photon entanglement source, we demonstrate quantum teleportation, closely following the original scheme, for any unknown state created outside, between two optical free-space links separated by 97 km. Over a 35-53 dB high-loss quantum channel, an average fidelity of 80....

  12. Teleportation of Squeezed Entangled State

    Institute of Scientific and Technical Information of China (English)

    HU Li-Yun; ZHOU Nan-Run

    2007-01-01

    Based on the coherent entangled state |α, x> we introduce the squeezed entangled state (SES). Then we propose a teleportation protocol for the SES by using Einstein-Podolsky-Rosen entangled state |η>as a quantum channel.The calculation is greatly simplified by virtue of the Schmidt decompositions of both |α, x>and |η>. Any bipartite states that can be expanded in terms of |α, x>may be teleported in this way due to the completeness of |α, x>.

  13. Research on tensor representation of quantum teleportation%张量表示的量子隐形传态研究

    Institute of Scientific and Technical Information of China (English)

    田秀劳; 胡洋; 符洪姿

    2014-01-01

    通过定义通道参数矩阵X、测量矩阵Tα和传输变换矩阵σα,介绍一种量子隐形传态的张量表示和分析方法,并用此方法来重新表示量子隐形传输、量子网络控制隐形传输、量子概率隐形传输和量子双向隐形传输。量子隐形传态的这种张量表示方法揭示了量子通道和测量方法之间的内在联系,能给出实现隐形传态时选取量子通道的一般判据。该方法使隐形传态的表示简洁明了,处理多粒子态的隐形传态更有优势。%The tensor representation is introduced to study quantum teleportation.Quantum channel parameter matrix X,measurement matrix Tαand transformation matrixσαare definited. With the tensor representation,the quantum telepoatation,the network-controlled telepoatation are reconsidered.This method of tensor representation recovers underlying relationship between the quantum channel and measurement and gives an effective criterion to choose the quantum channel for realizing the quantum telepoatation.The tensor representation can avoid tedious e-quation and complex calculations and make the teleportation processing succincter.

  14. Optimal teleportation with a noisy source

    Energy Technology Data Exchange (ETDEWEB)

    Taketani, Bruno G. [Instituto de Fisica, Universidade Federal do Rio de Janeiro, Rio de Janeiro (Brazil); Physikalisches Institut der Albert-Ludwigs-Universitaet, Freiburg im Breisgau (Germany); Melo, Fernando de [Instituut voor Theoretische Fysica, Katholieke Universiteit Leuven, Leuven, Belgie (Belgium); Physikalisches Institut der Albert-Ludwigs-Universitaet, Freiburg im Breisgau (Germany); Matos Filho, Ruynet L. de [Instituto de Fisica, Universidade Federal do Rio de Janeiro, Rio de Janeiro (Brazil)

    2012-07-01

    In this work we discuss the role of decoherence in quantum information protocols. Particularly, we study quantum teleportation in the realistic situation where not only the transmission channel is imperfect, but also the preparation of the state to be teleported. The optimal protocol to be applied in this situation is found and we show that taking into account the input state noise leads to sizable gains in teleportation fidelity. It is then evident that sources of noise in the input state preparation must be taken into consideration in order to maximize the teleportation fidelity. The optimization of the protocol can be defined for specific experimental realizations and accessible operations, giving a trade-off between protocol quality and experiment complexity.

  15. Probabilistic Teleportation of an Arbitrary Two-Atom State in Cavity QED

    Institute of Scientific and Technical Information of China (English)

    LIU Jin-Ming

    2007-01-01

    We propose a scheme for the teleportation of an arbitrary two-atom state by using two pairs of two-atom nonmaximally entangled states as the quantum channel in cavity QED.It is shown that no matter whether the arbitrary two-atom pure state to be teleported is entangled or not,our teleportation scheme can always be probabilistically realized.The success probability of teleportation is determined by the smaller coefficients of the two initially entangled atom pairs.

  16. Scheme for secure swapping two unknown states of a photonic qubit and an electron-spin qubit using simultaneous quantum transmission and teleportation via quantum dots inside single-sided optical cavities

    Energy Technology Data Exchange (ETDEWEB)

    Heo, Jino [College of Electrical and Computer Engineering, Chungbuk National University, Chungdae-ro 1, Seowon-Gu, Cheongju (Korea, Republic of); Kang, Min-Sung [Center for Quantum Information, Korea Institute of Science and Technology (KIST), Seoul, 136-791 (Korea, Republic of); Hong, Chang-Ho [National Security Research Institute, P.O.Box 1, Yuseong, Daejeon, 34188 (Korea, Republic of); Choi, Seong-Gon [College of Electrical and Computer Engineering, Chungbuk National University, Chungdae-ro 1, Seowon-Gu, Cheongju (Korea, Republic of); Hong, Jong-Phil, E-mail: jongph@cbnu.ac.kr [College of Electrical and Computer Engineering, Chungbuk National University, Chungdae-ro 1, Seowon-Gu, Cheongju (Korea, Republic of)

    2017-06-15

    We propose a scheme for swapping two unknown states of a photon and electron spin confined to a charged quantum dot (QD) between two users by transferring a single photon. This scheme simultaneously transfers and teleports an unknown state (electron spin) between two users. For this bidirectional quantum communication, we utilize the interactions between a photonic and an electron-spin qubits of a QD located inside a single-sided optical cavity. Thus, our proposal using QD-cavity systems can obtain a certain success probability with high fidelity. Furthermore, compared to a previous scheme using cross-Kerr nonlinearities and homodyne detections, our scheme (using QD-cavity systems) can improve the feasibility under the decoherence effect in practice. - Highlights: • Design of Simultaneous quantum transmission and teleportation scheme via quantum dots and cavities. • We have developed the experimental feasibility of this scheme compared with the existing scheme. • Analysis of some benefits when our scheme is experimentally implemented using quantum dots and single-sided cavities.

  17. Probabilistic Teleportation of a Four-Particle Entangled State

    Institute of Scientific and Technical Information of China (English)

    ZHAN You-Bang; FU Hao; DONG Zheng-Chao

    2005-01-01

    A Scheme for teleporting an unknown four-particle entangled state is proposed via entangled swapping. In this scheme, four pairs of entangled particles are used as quantum channel. It is shown that, if the four pairs of particles are nonmaximally entangled, the teleportation can be successfully realized with certain probability if a receiver adopts some appropriate unitary transformations.

  18. The dependence of fidelity on the squeezing parameter in teleportation of the squeezed coherent states

    Institute of Scientific and Technical Information of China (English)

    Zhang Jing-Tao; He Guang-Qiang; Ren Li-Jie; Zeng Gui-Hua

    2011-01-01

    This paper investigates an analytical expression of teleportation fidelity in the teleportation scheme of a single mode of electromagnetic field. The fidelity between the original squeezed coherent state and the teleported one is expressed in terms of the squeezing parameter r and the quantum channel parameter (two-mode squeezed state) p. The results of analysis show that the fidelity increases with the increase of the quantum channel parameter p, while the fidelity decreases with the increase of the squeezing parameter r of the squeezed state. Thus the coherent state (r = 0)is the best quantum signal for continuous variable quantum teleportation once the quantum channel is built.

  19. Entanglement Teleportation via a Two-Qubit System with Anisotropic Couplings under a Different Nonuniform Magnetic Field

    Institute of Scientific and Technical Information of China (English)

    QIN Meng

    2013-01-01

    We examine entanglement teleportation,characterized by average fidelity,of two-qubit XY Z spin chain under different nonuniform magnetic field.The entanglement teleportation and the fidelity of entanglement teleportation are investigated separately.We show explicitly that the fidelity of entanglement teleportation can be enhanced by changing the direction of the magnetic field.This means that we can always get optimal fidelity by choosing the directions of magnetic field in the process of quantum teleportation.Moreover,the results show that in some cases the ferromagnetic chain aiso is a quaiified candidate in the process of teleportation protocol.

  20. Dynamical quantum teleportation

    Energy Technology Data Exchange (ETDEWEB)

    Muschik, Christine [ICFO-Institut de Ciencies Fotoniques (Spain); Polzik, Eugene [Niels Bohr Institute (Denmark); Cirac, Ignacio [Max-Planck-Institute (Germany)

    2013-07-01

    We introduce two protocols for inducing non-local dynamics between two separate parties. The first scheme allows for the engineering of an interaction between the two remote systems, while the second protocol induces a dynamics in one of the parties, which is controlled by the other one. Both schemes apply to continuous variable systems, run continuously in time and are based on instantaneous feedback.

  1. A controlled quantum teleportation scheme with identity certification%一种可控量子隐形传态身份认证的方案

    Institute of Scientific and Technical Information of China (English)

    龚敬; 谭晓青

    2013-01-01

    提出了一种实现可控量子隐形传态身份认证的方案.可信第三方Charlie利用纠缠交换原理对接收者Bob进行身份认证,在确定Bob的合法身份并将消息反馈给发送者Alice后,Alice再对量子信息进行传送.本方案能有效解决假冒身份攻击,从而保证量子信息传送的安全性.%This paper proposed a controlled quantum teleportation scheme with identity certification. The receiver Bob was identified by entanglement swapping principle from the trusted Charlie. After the sender Alice gets the feedback from Charlie, and Charlie can make sure the identity of Bob and then send the quantum information to Bob. The scheme could prevent forgery attack effectively to ensure the security of quantum information transmission.

  2. Thermal entanglement and teleportation in a dipolar interacting system

    Energy Technology Data Exchange (ETDEWEB)

    Castro, C.S., E-mail: ccastro@if.uff.br [Instituto de Física, Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza s/n, Gragoatá, 24210-346 Niterói, RJ (Brazil); Centro de Formação de Professores, Universidade Federal do Recôncavo da Bahia, Av. Nestor de Mello Pita, n. 535, 45.300-000 Amargosa, BA (Brazil); Duarte, O.S.; Pires, D.P.; Soares-Pinto, D.O. [Instituto de Física de São Carlos, Universidade de São Paulo, P.O. Box 369, São Carlos, 13560-970 SP (Brazil); Reis, M.S. [Instituto de Física, Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza s/n, Gragoatá, 24210-346 Niterói, RJ (Brazil)

    2016-04-22

    Quantum teleportation, which depends on entangled states, is a fascinating subject and an important branch of quantum information processing. The present work reports the use of a dipolar spin thermal system as a noisy quantum channel to perform quantum teleportation. Non-locality, tested by violation of Bell's inequality and thermal entanglement, measured by negativity, shows that for the present model all entangled states, even those that do not violate Bell's inequality, are useful for teleportation. - Highlights: • The effects of a dipolar interaction between two spins on their degree of entanglement and non-locality is reported. • The model presents some degree of non-locality and entanglement at a given coupling parameters. • It is shown how the magnetic anisotropies can influence the fidelity of teleportation.

  3. Teleportation for an Ionic Entangled Internal State by Entanglement Swapping

    Institute of Scientific and Technical Information of China (English)

    ZHENG Xiao-Juan; FANG Mao-Fa; LIAO Xiang-Ping; CAI Jian-Wu

    2006-01-01

    @@ We present an effective scheme to teleport an unknown ionic entangled internal state via trapped ions without joint Bell-state measurement. In the constructed quantum channel process, we adopt entanglement swapping to avoid decrease of entanglement during the distribution of particles. Thus our scheme provides new prospects for quantum teleportation over longer distance. The distinct advantages of our scheme are that our scheme is insensitive to heating of vibrational mode and can be generalized to teleport an N-ion electronic entangled GHZ class state. Furthermore, in our scheme the success probability can reach 1.

  4. Deterministic Multi-hop Controlled Teleportation of Arbitrary Single-Qubit State

    Science.gov (United States)

    Peng, Jia-yin; Bai, Ming-qiang; Mo, Zhi-wen

    2017-10-01

    Multi-hop teleportation is of great significance due to long-distance delivery of quantum information and wireless quantum communication networks. In existing protocols of multi-hop teleportation, the more nodes, the smaller the success probability. In this paper, fusing the ideas of multi-hop teleportation and controlled teleportation, we put forward a scheme for implementing multi-hop controlled teleportation of single-qubit state. A set of ingenious three-qubit non-maximally entangled states are constructed to serve as the quantum channels. The information is perfectly transmitted hop by hop through teleportation under the control of the supervisors. Unit success probability can be achieved independent of channel's entanglement degree and the number of intermediate nodes. Only Pauli operations, single-qubit rotation, Hadamard gate, controlled-NOT gate, Bell-state measurement and single-qubit measurement are used in our scheme, so this scheme is easily realized in physical experiment.

  5. Notes on teleportation in an expanding space

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Jun, E-mail: tsunfeng@iphy.ac.cn [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Yang, Wen-Li [Institute of Modern Physics, Northwest University, Xian 710069 (China); Zhang, Yao-Zhong [School of Mathematics and Physics, The University of Queensland, Brisbane, QLD 4072 (Australia); Fan, Heng, E-mail: hfan@iphy.ac.cn [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2013-02-26

    We investigate the quantum teleportation between a conformal detector Alice and an inertial detector Bob in de Sitter space in two schemes, (i) one uses free scalar modes and (ii) one utilizes cavity to store qubit. We show that the fidelity of the teleportation is degraded for Bob in both cases. While the fidelity-loss is due to the Gibbons–Hawking effect associated with his cosmological horizon in the scheme (i), the entanglement decreases in the scheme (ii) because the ability to entangle the cavities is reduced by the spacetime curvature. With a cutoff at Planck-scale, comparing with the standard Bunch–Davies choice, we also show that the possible Planckian physics cause extra modifications to the fidelity of the teleportation protocol in both schemes.

  6. Teleportation of a multiqubit state by an entangled qudit channel

    Institute of Scientific and Technical Information of China (English)

    郑亦庄; 顾永建; 吴桂初; 郭光灿

    2003-01-01

    We investigate the problem of teleportation of an M-qubit state by using an entangled qudit pair as a quantum channe; and show that the teleportation of a multiparticle state can correspond to the teleportation of a multidimensional state.We also introduce a quantum-state converter composed of beamspliter arrays,on /off -detectors and coross-Kerr couplers and demonstrate that the stte concersion from an M-qubit to an N-dimensional qudit and vice versa can be implemented with this converter,where N=2M,Based on this ,an experimentallu feasible for the teleportation of an M-qubit via an entangl;ed N-level qudit pair channel is proposed.

  7. Probabilistic teleportation of multi-particle partially entangled state

    Institute of Scientific and Technical Information of China (English)

    Chen Xiu-Bo; Du Jian-Zhong; Wen Qiao-Yan; Zhu Fu-Chen

    2008-01-01

    Utilizing the generalized measurement described by positive operator-valued measure, this paper comes up with a protocol for teleportation of an unknown multi-particle entangled (GHZ) state with a certain probability. The feature of the present protocol is to weaken requirement for the quantum channel initially shared by sender and receiver. All unitary transformations performed by receiver are summarized into a formula. On the other hand, this paper explicitlyconstructs the efficient quantum circuits for implementing the proposed teleportation by means of universal quantum logic operations in quantum computation.

  8. Improving fidelity in atomic state teleportation via cavity decay

    OpenAIRE

    Chimczak, Grzegorz; Tanaś, Ryszard

    2007-01-01

    We propose a modified protocol of atomic state teleportation for the scheme proposed by Bose et al. (Phys. Rev. Lett. 83, 5158 (1999)). The modified protocol involves an additional stage in which quantum information distorted during the first stage is fully recovered by a compensation of the damping factor. The modification makes it possible to obtain a high fidelity of teleported state for cavities that are much worse than that required in the original protocol, i.e., their decay rates can b...

  9. Teleporting squeezing: Optimization using non-Gaussian resources

    CERN Document Server

    Dell'Anno, F; Adesso, G; Illuminati, F

    2010-01-01

    We study the continuous-variable quantum teleportation of states, statistical moments of observables, and scale parameters such as squeezing. We investigate the problem both in ideal and imperfect Vaidman-Braunstein-Kimble protocol setups. We show how the teleportation fidelity is maximized and the difference between output and input variances is minimized by using suitably optimized entangled resources. Specifically, we consider the teleportation of coherent squeezed states, exploiting squeezed Bell states as entangled resources. This class of non-Gaussian states includes photon-added and photon-subtracted squeezed states as special cases. At variance with the case of entangled Gaussian resources, the use of entangled non-Gaussian squeezed Bell resources allows for different optimization procedures that lead to inequivalent results. Performing two independent optimization procedures one can either maximize the state teleportation fidelity, or minimize the difference between input and output quadrature varian...

  10. Two Versions of the Projection Postulate: From EPR Argument to One-Way Quantum Computing and Teleportation

    Directory of Open Access Journals (Sweden)

    Andrei Khrennikov

    2010-01-01

    of the projection postulate (due to von Neumann and Lüders should be taken into account seriously in the analysis of the basic constructions of quantum information theory. This paper is a review devoted to such an analysis.

  11. Teleportation of a two-particle four-component squeezed vacuum state by linear optical elements

    Institute of Scientific and Technical Information of China (English)

    Huina Chen; Jinming Liu

    2009-01-01

    We present a linear optical scheme for achieving a unity fidelity teleportation of a two-particle four component squeezed vacuum state using two entangled squeezed vacuum states as quantum channel.The devices used are beam splitters and ideal photon detectors capable of distinguishing between odd and even photon numbers.Moreover,we also obtain the success probability of the teleportation scheme.

  12. Probabilistic Teleportation of the Three-Particle Entangled State viaEntanglement Swapping

    Institute of Scientific and Technical Information of China (English)

    路洪

    2001-01-01

    A scheme of teleportation of a three-particle entangled state via entanglement swapping is proposed. It is shown that if a two-particle entangled state and a three-particle entangled state (both are not maximum entangled states) are used as quantum channels, probabilistic teleportation of the three-particle entangled state can be realized.

  13. Teleportation via thermally entangled states of a two-qubit Heisenberg XXZ chain

    Institute of Scientific and Technical Information of China (English)

    QIN Meng; TAO Ying-Juan; TIAN Dong-Ping

    2008-01-01

    We investigate quantum teleportation as a tool to study the thermally entangled state of a twoqubit Heisenberg XXZ chain.Our work is mainly to investigate the characteristics of a Heisenberg XXZ chain and get some analytical results of the fully entangled fraction.We also consider the entanglement teleportation via a two-qubit Heisenberg XXZ chain.

  14. Teleportation of N-particle entangled W state via entanglement swapping

    Institute of Scientific and Technical Information of China (English)

    Zhan You-Bang

    2004-01-01

    A scheme for teleporting an unknown N-particle entangled W state is proposed via entanglement swapping. In this scheme, N maximally entangled particle pairs are used as quantum channel. As a special case, the teleportation of an unknown four-particle entangled W state is studied.

  15. Role of syndrome information on a one-way quantum repeater using teleportation-based error correction

    Science.gov (United States)

    Namiki, Ryo; Jiang, Liang; Kim, Jungsang; Lütkenhaus, Norbert

    2016-11-01

    We investigate a quantum repeater scheme for quantum key distribution based on the work by S. Muralidharan et al. [Phys. Rev. Lett. 112, 250501 (2014)], 10.1103/PhysRevLett.112.250501. Our scheme extends that work by making use of error syndrome measurement outcomes available at the repeater stations. We show how to calculate the secret key rates for the case of optimizing the syndrome information, while the known key rate is based on a scenario of coarse graining the syndrome information. We show that these key rates can surpass the Pirandola-Laurenza-Ottaviani-Banchi bound on secret key rates of direct transmission over lossy bosonic channels.

  16. Dark Energy from Quantum Matter

    CERN Document Server

    Dappiaggi, Claudio; Möller, Jan; Pinamonti, Nicola

    2010-01-01

    We study the backreaction of free quantum fields on a flat Robertson-Walker spacetime. Apart from renormalization freedom, the vacuum energy receives contributions from both the trace anomaly and the thermal nature of the quantum state. The former represents a dynamical realisation of dark energy, while the latter mimics an effective dark matter component. The semiclassical dynamics yield two classes of asymptotically stable solutions. The first reproduces the concordance model in a suitable regime. The second lacks a classical counterpart, but is in excellent agreement with recent observations.

  17. Dark energy from quantum matter

    Energy Technology Data Exchange (ETDEWEB)

    Dappiaggi, Claudio; Hack, Thomas-Paul [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Moeller, Jan [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Gruppe Theorie; Pinamonti, Nicola [Rome-2 Univ. (Italy). Dipt. di Matematica

    2010-07-15

    We study the backreaction of free quantum fields on a flat Robertson-Walker spacetime. Apart from renormalization freedom, the vacuum energy receives contributions from both the trace anomaly and the thermal nature of the quantum state. The former represents a dynamical realisation of dark energy, while the latter mimics an effective dark matter component. The semiclassical dynamics yield two classes of asymptotically stable solutions. The first reproduces the CDM model in a suitable regime. The second lacks a classical counterpart, but is in excellent agreement with recent observations. (orig.)

  18. Quantum scattering at low energies

    DEFF Research Database (Denmark)

    Derezinski, Jan; Skibsted, Erik

    For a class of negative slowly decaying potentials, including with , we study the quantum mechanical scattering theory in the low-energy regime. Using modifiers of the Isozaki--Kitada type we show that scattering theory is well behaved on the {\\it whole} continuous spectrum of the Hamiltonian...

  19. Slow light invisibility, teleportation, and other mysteries of light

    CERN Document Server

    Perkowitz, Sidney

    2011-01-01

    Slow Light is a popular treatment of today's astonishing breakthroughs in the science of light. Even though we don't understand light's quantum mysteries, we can slow it to a stop and speed it up beyond its Einsteinian speed limit, 186,000 miles/sec; use it for quantum telecommunications; teleport it; manipulate it to create invisibility; and perhaps generate hydrogen fusion power with it. All this is lucidly presented for non-scientists who wonder about teleportation, Harry Potter invisibility cloaks, and other fantastic outcomes. Slow Light shows how the real science and the fantasy inspire

  20. Probabilistic Teleportation of a Four-Particle Entangled W State

    Institute of Scientific and Technical Information of China (English)

    ZHAN You-Bang; FU Hao

    2005-01-01

    In this paper, two schemes for teleporting an unknown four-particle entangled W state is proposed. In the first scheme, two partial entangled four-particle states are used as quantum channels, while in the second scheme,four non-maximally entangled particle pairs are considered as quantum channels. It is shown that the teleportation can be successfully realized with certain probability, for both schemes, if a receiver adopts some appropriate unitary transformations. It is also shown that the successful probabilities of these two schemes are different.

  1. Teleportation of an arbitrary three-particle state

    Institute of Scientific and Technical Information of China (English)

    陈立冰

    2002-01-01

    We propose two schemes for teleporting an arbitrary three-particle state. In the first scheme, a two-particle state and a three-particle entangled state (both non-maximally entangled states) are used as quantum channels, while in the second scheme, three non-maximally entangled particle pairs are employed as quantum channels. We show that teleportation can be successfully realized with certain probability if a receiver adopts some appropriate unitary transformations. Their success probabilities and the classical communication costs are different.

  2. Teleporting N-qubit unknown atomic state by utilizing the Ⅴ-type three-level atom

    Institute of Scientific and Technical Information of China (English)

    ZHANG XinHua; YANG ZhiYong; XU PeiPei

    2009-01-01

    Realizing the teleportation of quantum state, especially the teleportation of N-qubit quantum state, is of great importance in quantum information. In this paper, Raman-interaction of the Ⅴ-type degenerate three-level atom and single-mode cavity field is studied by utilizing complete quantum theory. Then a new scheme for teleporting N-qubit unknown atomic state via Raman-interaction of the Ⅴ-type degen-erate three-level atom with a single-mode cavity field is proposed, which is based upon the complete quantum theory mentioned above.

  3. Teleporting N-qubit unknown atomic state by utilizing the V-type three-level atom

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Realizing the teleportation of quantum state, especially the teleportation of N-qubit quantum state, is of great importance in quantum information. In this paper, Raman-interaction of the V-type degenerate three-level atom and single-mode cavity field is studied by utilizing complete quantum theory. Then a new scheme for teleporting N-qubit unknown atomic state via Raman-interaction of the V-type degenerate three-level atom with a single-mode cavity field is proposed, which is based upon the complete quantum theory mentioned above.

  4. Teleportation of entanglement over 143 km

    CERN Document Server

    Herbst, Thomas; Fink, Matthias; Handsteiner, Johannes; Wittmann, Bernhard; Ursin, Rupert; Zeilinger, Anton

    2014-01-01

    As a direct consequence of the no-cloning theorem, the deterministic amplification as in classical communication is impossible for quantum states. This calls for more advanced techniques in a future global quantum network, e.g. for cloud quantum computing. A unique solution is the teleportation of an entangled state, i.e. entanglement swapping, representing the central resource to relay entanglement between distant nodes. Together with entanglement purification and a quantum memory it constitutes a so-called quantum repeater. Since the afore mentioned building blocks have been individually demonstrated in laboratory setups only, the applicability of the required technology in real-world scenarios remained to be proven. Here we present a free-space entanglement-swapping experiment between the Canary Islands of La Palma and Tenerife, verifying the presence of quantum entanglement between two previously independent photons separated by 143 km. We obtained an expectation value for the entanglement-witness operato...

  5. Enhanced sensing and communication via quantum networks

    Science.gov (United States)

    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.

  6. Optimal use of multipartite entanglement for continuous variable teleportation

    CERN Document Server

    Adesso, G; Adesso, Gerardo; Illuminati, Fabrizio

    2004-01-01

    In this work we point out how the continuous variable teleportation protocol takes advantage of the quadrature entanglement in different ways, depending on the preparation of the entangled state. For a given amount of the entanglement resource, we describe the best production scheme for a two-mode Gaussian state, which enables quantum teleportation with optimal fidelity. We extend this study to multiparty entangled Gaussian states and define an operative measure of multipartite entanglement related to the optimal fidelity in a quantum teleportation network experiment. This optimal fidelity is shown to be equivalent to the entanglement of formation for the standard two-user protocol, and to the multipartite localizable entanglement for the multiuser protocol.

  7. Quantum entanglement

    CERN Document Server

    Horodecki, R; Horodecki, M; Horodecki, K; Horodecki, Ryszard; Horodecki, Pawel; Horodecki, Michal; Horodecki, Karol

    2007-01-01

    All our former experience with application of quantum theory seems to say: {\\it what is predicted by quantum formalism must occur in laboratory}. But the essence of quantum formalism - entanglement, recognized by Einstein, Podolsky, Rosen and Schr\\"odinger - waited over 70 years to enter to laboratories as a new resource as real as energy. This holistic property of compound quantum systems, which involves nonclassical correlations between subsystems, is a potential for many quantum processes, including ``canonical'' ones: quantum cryptography, quantum teleportation and dense coding. However, it appeared that this new resource is very complex and difficult to detect. Being usually fragile to environment, it is robust against conceptual and mathematical tools, the task of which is to decipher its rich structure. This article reviews basic aspects of entanglement including its characterization, detection, distillation and quantifying. In particular, the authors discuss various manifestations of entanglement via ...

  8. Teleportation of an unknown bipartite state via non-maximally entangled two-particle state

    Institute of Scientific and Technical Information of China (English)

    Cao Hai-Jing; Guo Yan-Qing; Song He-Shan

    2006-01-01

    In this paper a new scheme for teleporting an unknown entangled state of two particles is proposed. To weaken the requirement for the quantum channel, without loss of generality, two communicators only share a non-maximally entangled two-particle state. Teleportation can be probabilistically realized if sender performs Bell-state measurements and Hadamard transformation and receiver introduces two auxiliary particles, operates G-not operation, single-qubit measurements and appropriate unitary transformations. The probability of successful teleportation is determined by the smaller one among the coefficients' absolute values of the quantum channel.

  9. Probabilistic Teleportation of an Arbitrary Three-Level Two-Particle State and Classical Communication Cost

    Institute of Scientific and Technical Information of China (English)

    DAIHong-Yi; KUANGLe-Man; LICheng-Zu

    2005-01-01

    We propose a scheme to probabilistically teleport an unknown arbitrary three-level two-particle state by using two partial entangled two-particle states of three-level as the quantum channel. The classical communication cost required in the ideal probabilistic teleportation process is also calculated. This scheme can be directly generalized to teleport an unknown and arbitrary three-level K-particle state by using K partial entangled two-particle states of three-level as the quantum channel.

  10. Energy-efficient quantum computing

    Science.gov (United States)

    Ikonen, Joni; Salmilehto, Juha; Möttönen, Mikko

    2017-04-01

    In the near future, one of the major challenges in the realization of large-scale quantum computers operating at low temperatures is the management of harmful heat loads owing to thermal conduction of cabling and dissipation at cryogenic components. This naturally raises the question that what are the fundamental limitations of energy consumption in scalable quantum computing. In this work, we derive the greatest lower bound for the gate error induced by a single application of a bosonic drive mode of given energy. Previously, such an error type has been considered to be inversely proportional to the total driving power, but we show that this limitation can be circumvented by introducing a qubit driving scheme which reuses and corrects drive pulses. Specifically, our method serves to reduce the average energy consumption per gate operation without increasing the average gate error. Thus our work shows that precise, scalable control of quantum systems can, in principle, be implemented without the introduction of excessive heat or decoherence.

  11. Teleportation of a Kind of Three-Mode Entangled States of Continuous Variables

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    A quantum teleportation scheme to teleport a kind of tripartite entangled states of continuous variables by using a quantum channel composed of three bipartite entangled states is proposed. The joint Bell measurement is feasible because the bipartite entangled states are complete and the squeezed state has a natural representation in the entangled state basis. The calculation is greatly simplified by using the Schmidt decomposition of the entangled states.

  12. Two schemes of perfect teleportation one-particle state by a three-particle general W state

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In teleportation, it can be seen that the probability of success is determined by Alice's measurement and quantum channel. If the Alice's measurement is appropriate, the teleportation can be successfully realized with the maximal probability. In accordance with transformation operator, two schemes are proposed for teleportation of an unknown one-particle state via a general W state, through which the successful probability and the fidelity of both schemes reach 1. Furthermore, two optimal matches of orthogonal complete measurement bases are given for teleporting an unknown one-particle state.

  13. Teleportation of atomic entangled states with a thermal cavity

    Institute of Scientific and Technical Information of China (English)

    Zheng Xiao-Juan; Fang Mao-Fa; Cai Jian-Wu; Liao Xiang-Ping

    2006-01-01

    We propose a most simple and experimentally feasible scheme for teleporting unknown atomic entangled states in driven cavity quantum electrodynamics (QED). In our scheme, the joint Bell-state measurement (BSM) is not required,and the successful probability can reach 1.0. Furthermore, the scheme is insensitive to the cavity decay and the thermal field.

  14. Deterministic teleportation using single-photon entanglement as a resource

    DEFF Research Database (Denmark)

    Björk, Gunnar; Laghaout, Amine; Andersen, Ulrik L.

    2012-01-01

    We outline a proof that teleportation with a single particle is, in principle, just as reliable as with two particles. We thereby hope to dispel the skepticism surrounding single-photon entanglement as a valid resource in quantum information. A deterministic Bell-state analyzer is proposed which...

  15. Enhancing teleportation fidelity by means of weak measurements or reversal

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Liang, E-mail: lqiu@cumt.edu.cn [College of Sciences, China University of Mining and Technology, Xuzhou 221116 (China); Tang, Gang; Yang, Xianqing [College of Sciences, China University of Mining and Technology, Xuzhou 221116 (China); Wang, Anmin [Department of Modern Physics, University of Science and Technology of China, Hefei 230026 (China)

    2014-11-15

    The enhancement of teleportation fidelity by weak measurement or quantum measurement reversal is investigated. One qubit of a maximally entangled state undergoes the amplitude damping, and the subsequent application of weak measurement or quantum measurement reversal could improve the teleportation fidelity beyond the classical region. The improvement could not be attributed to the increasing of entanglement, quantum discord, classical correlation or total correlation. We declare that it should be owed to the probabilistic nature of the method. - Highlights: • The method’s probabilistic nature should be responsible for the improvement. • Quantum or classical correlation cannot explain the improvement. • The receiver cannot apply weak measurements. • The sender’s quantum measurement reversal is only useful for |Ψ{sup ±}〉.

  16. Teleportation of M-Qubit Unitary Operations

    Institute of Scientific and Technical Information of China (English)

    郑亦庄; 顾永建; 郭光灿

    2002-01-01

    We discuss teleportation of unitary operations on a two-qubit in detail, then generalize the bidirectional state teleportation scheme from one-qubit to M-qubit unitary operations. The resources required for the optimal implementation of teleportation of an M-qubit unitary operation using a bidirectional state teleportation scheme are given.

  17. Probabilistic teleportation of an arbitrary three-particle state

    Institute of Scientific and Technical Information of China (English)

    Lin Xiu; Li Hong-Cai

    2005-01-01

    A scheme for teleporting an arbitrary and unknown three-particle state from a sender to either one of two receivers is proposed. The quantum channel is composed of a two-particle non-maximally entangled state and two three-particle non-maximally entangled W states. An arbitrary three-particle state can be perfectly teleported probabilistically if the sender performs three generalized Bell-state measurements and sends to the two receivers the classical result of these measurements, and either one of the two receivers adopts an appropriate unitary transformation conditioned on the suitable measurement outcomes of the other receiver. All kinds of unitary transformations are given in detail.

  18. Comment on "Fractional quantum mechanics" and "Fractional Schrödinger equation"

    Science.gov (United States)

    Wei, Yuchuan

    2016-06-01

    In this Comment we point out some shortcomings in two papers [N. Laskin, Phys. Rev. E 62, 3135 (2000), 10.1103/PhysRevE.62.3135; N. Laskin, Phys. Rev. E 66, 056108 (2002), 10.1103/PhysRevE.66.056108]. We prove that the fractional uncertainty relation does not hold generally. The probability continuity equation in fractional quantum mechanics has a missing source term, which leads to particle teleportation, i.e., a particle can teleport from a place to another. Since the relativistic kinetic energy can be viewed as an approximate realization of the fractional kinetic energy, the particle teleportation should be an observable relativistic effect in quantum mechanics. With the help of this concept, superconductivity could be viewed as the teleportation of electrons from one side of a superconductor to another and superfluidity could be viewed as the teleportation of helium atoms from one end of a capillary tube to the other. We also point out how to teleport a particle to an arbitrary destination.

  19. Comment on "Fractional quantum mechanics" and "Fractional Schrödinger equation".

    Science.gov (United States)

    Wei, Yuchuan

    2016-06-01

    In this Comment we point out some shortcomings in two papers [N. Laskin, Phys. Rev. E 62, 3135 (2000)10.1103/PhysRevE.62.3135; N. Laskin, Phys. Rev. E 66, 056108 (2002)10.1103/PhysRevE.66.056108]. We prove that the fractional uncertainty relation does not hold generally. The probability continuity equation in fractional quantum mechanics has a missing source term, which leads to particle teleportation, i.e., a particle can teleport from a place to another. Since the relativistic kinetic energy can be viewed as an approximate realization of the fractional kinetic energy, the particle teleportation should be an observable relativistic effect in quantum mechanics. With the help of this concept, superconductivity could be viewed as the teleportation of electrons from one side of a superconductor to another and superfluidity could be viewed as the teleportation of helium atoms from one end of a capillary tube to the other. We also point out how to teleport a particle to an arbitrary destination.

  20. Polarization enhancement in (d)over-right-arrow((p)over-right-arrow,(n)over-right-arrow)He-2 reaction : nuclear teleportation

    NARCIS (Netherlands)

    Hamieh, S

    2004-01-01

    I show that an experimental technique used in nuclear physics may be successfully applied to quantum teleportation (QT) of spin states of massive matter. A new non-local physical effect, the 'quantum-teleportation effect', is discovered for the nuclear polarization measurement. Enhancement of the ne

  1. Pyroelectric Quantum Well Energy Harvesters Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose the investigation of pyroelectric energy harvesters with enhanced efficiencies through quantum wells induced by a multilayer design.  Pyroelectric...

  2. Teleportation of a qubit using entangled non-orthogonal states: a comparative study

    Science.gov (United States)

    Sisodia, Mitali; Verma, Vikram; Thapliyal, Kishore; Pathak, Anirban

    2017-03-01

    The effect of non-orthogonality of an entangled non-orthogonal state-based quantum channel is investigated in detail in the context of the teleportation of a qubit. Specifically, average fidelity, minimum fidelity and minimum assured fidelity (MASFI) are obtained for teleportation of a single-qubit state using all the Bell-type entangled non-orthogonal states known as quasi-Bell states. Using Horodecki criterion, it is shown that the teleportation scheme obtained by replacing the quantum channel (Bell state) of the usual teleportation scheme by a quasi-Bell state is optimal. Further, the performance of various quasi-Bell states as teleportation channel is compared in an ideal situation (i.e., in the absence of noise) and under different noise models (e.g., amplitude and phase damping channels). It is observed that the best choice of the quasi-Bell state depends on the amount non-orthogonality, both in noisy and noiseless case. A specific quasi-Bell state, which was found to be maximally entangled in the ideal conditions, is shown to be less efficient as a teleportation channel compared to other quasi-Bell states in particular cases when subjected to noisy channels. It has also been observed that usually the value of average fidelity falls with an increase in the number of qubits exposed to noisy channels (viz., Alice's, Bob's and to be teleported qubits), but the converse may be observed in some particular cases.

  3. Teleportation of N-Particle Entangled GHZ State via Entanglement Swapping

    Institute of Scientific and Technical Information of China (English)

    SHA Jin-Qiao; FANG Jian-Xing; ZHU Shi-Qun; JIANG Wei-Xing; QIAN Xue-Min

    2006-01-01

    In this scheme, N non-maximally entangled particle pairs are used as quantum channel to teleport an unknown N-particle entangled GHZ state via entanglement swapping. In order to realize this teleportation, the sender Alice operates Bell-state measurement on particles belonging to herself. Then she informs the results to the receiver Bob through classical communication. According to the results, Bob operates corresponding transformation to reconstruct the initial state. The advantage of this scheme is that it needs only one common unitary matrix for Alice's different results, which has a more general meaning. As a special case, teleporting an unknown three-particle entangled GHZ state is proposed.

  4. Teleportation of n-Particle State via n Pairs of EPR Channels

    Institute of Scientific and Technical Information of China (English)

    CAO Min; ZHU Shi-Qun; FANG Jian-Xing

    2004-01-01

    The teleportation of an arbitrary n-particle state (n ≥ 1) is proposed if n pairs of identical EPR states are utilized as quantum channels. Independent Bell state measurements are performed for joint measurement. By using a special Latin square of order 2n(n ≥ 1), explicit expressions of outcomes after the Bell state measurements by Alice (sender) and the corresponding unitary transformations by Bob (receiver) can be derived. It is shown that the teleportation of n-particle state can be implemented by a series of single-qubit teleportation.

  5. Demonstrating nonlocality-induced teleportation through Majorana bound states in a semiconductor nanowire

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Peiyue [Department of Physics, Beijing Normal University, Beijing 100875 (China); Cao, Yunshan [School of Physics, Peking University, Beijing 100871 (China); Kavli Institute of NanoScience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft (Netherlands); Gong, Ming [Department of Physics and Centre for Quantum Coherence, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong (China); Li, Shu-Shen [State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China); Li, Xin-Qi, E-mail: lixinqi@bnu.edu.cn [Department of Physics, Beijing Normal University, Beijing 100875 (China)

    2014-02-01

    It was predicted by Tewari et al. (2008) [15] that a teleportation-like electron transfer phenomenon is one of the novel consequences of the existence of Majorana fermion, because of the inherently nonlocal nature. In this work we consider a concrete realization and measurement scheme for this interesting behavior, based on a setup consisting of a pair of quantum dots which are tunnel-coupled to a semiconductor nanowire and are jointly measured by two point-contact detectors. We analyze the teleportation dynamics in the presence of measurement back-action and discuss how the teleportation events can be identified from the current trajectories of strong response detectors.

  6. Quantum computer for dummies (in Russian)

    OpenAIRE

    Grozin, Andrey

    2011-01-01

    An introduction (in Russian) to quantum computers, quantum cryptography, and quantum teleportation for students who have no previous knowledge of these subjects, but know quantum mechanics. Several simple examples are considered in detail using the quantum computer emulator QCL.

  7. Cooperative Communications via Dual-Teleportation with Non-maximally Entanglement Measurements

    Institute of Scientific and Technical Information of China (English)

    毛云; 郭迎; 曾贵华

    2012-01-01

    We investigate a framework of the cooperative quantum teleportation (CQT) based on non-maximally entangled state basis (NB) measurements,instead of maximally entangled state basis (MB) measurements.It is implemented with two consecutive conventional (or direct) quantum telportations (DQT),where unknown quantum states can be transmitted in a point-to-point fashion.The security is based on the quantum-mechanical impossibility of local unitary transformations between non-maximally entangled states.It shows that the CQT can enhance the successful transmissions by self-correcting the errors introduced in the dual-teleportations.

  8. Entanglement concentration and teleportation of multipartite entangled states in an ion trap

    Institute of Scientific and Technical Information of China (English)

    Pan Chang-Ning; Fang Mao-Fa

    2007-01-01

    We propose an effective scheme for the entanglement concentration of a four-particle state via entanglement swapping in an ion trap. Taking the maximally entangled state after concentration as a quantum channel, we can faithfully and determinatively teleport quantum entangled states from Alice to Bob without the joint Bell-state measurement. In the process of constructing the quantum channel, we adopt entanglement swapping to avoid the decrease of entanglement during the distribution of particles. Thus our scheme provides a new prospect for quantum teleportation over a longer distance. Furthermore, the success probability of our scheme is 1.0.

  9. Scalable Quantum Simulation of Molecular Energies

    CERN Document Server

    O'Malley, P J J; Kivlichan, I D; Romero, J; McClean, J R; Barends, R; Kelly, J; Roushan, P; Tranter, A; Ding, N; Campbell, B; Chen, Y; Chen, Z; Chiaro, B; Dunsworth, A; Fowler, A G; Jeffrey, E; Megrant, A; Mutus, J Y; Neill, C; Quintana, C; Sank, D; Vainsencher, A; Wenner, J; White, T C; Coveney, P V; Love, P J; Neven, H; Aspuru-Guzik, A; Martinis, J M

    2015-01-01

    We report the first electronic structure calculation performed on a quantum computer without exponentially costly precompilation. We use a programmable array of superconducting qubits to compute the energy surface of molecular hydrogen using two distinct quantum algorithms. First, we experimentally execute the unitary coupled cluster method using the variational quantum eigensolver. Our efficient implementation predicts the correct dissociation energy to within chemical accuracy of the numerically exact result. Next, we experimentally demonstrate the canonical quantum algorithm for chemistry, which consists of Trotterization and quantum phase estimation. We compare the experimental performance of these approaches to show clear evidence that the variational quantum eigensolver is robust to certain errors, inspiring hope that quantum simulation of classically intractable molecules may be viable in the near future.

  10. Simulated Quantum Computation of Molecular Energies

    CERN Document Server

    Aspuru-Guzik, A; Love, P J; Head-Gordon, M; Aspuru-Guzik, Al\\'an; Dutoi, Anthony D.; Love, Peter J.; Head-Gordon, Martin

    2005-01-01

    The calculation time for the energy of atoms and molecules scales exponentially with system size on a classical computer but polynomially using quantum algorithms. We demonstrate that such algorithms can be applied to problems of chemical interest using modest numbers of quantum bits. Calculations of the water and lithium hydride molecular ground-state energies have been carried out on a quantum computer simulator using a recursive phase-estimation algorithm. The recursive algorithm reduces the number of quantum bits required for the readout register from about 20 to 4. Mappings of the molecular wave function to the quantum bits are described. An adiabatic method for the preparation of a good approximate ground-state wave function is described and demonstrated for a stretched hydrogen molecule. The number of quantum bits required scales linearly with the number of basis functions, and the number of gates required grows polynomially with the number of quantum bits.

  11. Probabilistic teleportation scheme of two-mode entangled photon states by using linear optic element

    Institute of Scientific and Technical Information of China (English)

    XIANG Shao-hua

    2003-01-01

    A scheme for teleporting two-mode entangled photon states with the successful probability 33.3% is proposed. In the scheme, the teleporte d qubit is two-mode photon entangled states, and two pairs of EPR pair are used as quantum channel between a sender and a receiver. This procedure is achieved by using two 50/50 symmetric beam splitters and four photon number detectors wit h the help of classical information.

  12. Thermoelectric energy harvesting with quantum dots.

    Science.gov (United States)

    Sothmann, Björn; Sánchez, Rafael; Jordan, Andrew N

    2015-01-21

    We review recent theoretical work on thermoelectric energy harvesting in multi-terminal quantum-dot setups. We first discuss several examples of nanoscale heat engines based on Coulomb-coupled conductors. In particular, we focus on quantum dots in the Coulomb-blockade regime, chaotic cavities and resonant tunneling through quantum dots and wells. We then turn toward quantum-dot heat engines that are driven by bosonic degrees of freedom such as phonons, magnons and microwave photons. These systems provide interesting connections to spin caloritronics and circuit quantum electrodynamics.

  13. Teleportation of entanglement over 143 km.

    Science.gov (United States)

    Herbst, Thomas; Scheidl, Thomas; Fink, Matthias; Handsteiner, Johannes; Wittmann, Bernhard; Ursin, Rupert; Zeilinger, Anton

    2015-11-17

    As a direct consequence of the no-cloning theorem, the deterministic amplification as in classical communication is impossible for unknown quantum states. This calls for more advanced techniques in a future global quantum network, e.g., for cloud quantum computing. A unique solution is the teleportation of an entangled state, i.e., entanglement swapping, representing the central resource to relay entanglement between distant nodes. Together with entanglement purification and a quantum memory it constitutes a so-called quantum repeater. Since the aforementioned building blocks have been individually demonstrated in laboratory setups only, the applicability of the required technology in real-world scenarios remained to be proven. Here we present a free-space entanglement-swapping experiment between the Canary Islands of La Palma and Tenerife, verifying the presence of quantum entanglement between two previously independent photons separated by 143 km. We obtained an expectation value for the entanglement-witness operator, more than 6 SDs beyond the classical limit. By consecutive generation of the two required photon pairs and space-like separation of the relevant measurement events, we also showed the feasibility of the swapping protocol in a long-distance scenario, where the independence of the nodes is highly demanded. Because our results already allow for efficient implementation of entanglement purification, we anticipate our research to lay the ground for a fully fledged quantum repeater over a realistic high-loss and even turbulent quantum channel.

  14. Dark Energy from Quantum Uncertainty of Simultaneity

    CERN Document Server

    Luo, M J

    2014-01-01

    The observed acceleration expansion of the universe was thought attribute to a mysterious dark energy in the framework of the classical general relativity. The dark energy behaves very similar with a vacuum energy in quantum mechanics. However, once the quantum effects are seriously taken into account, it predicts a wrong order of the vacuum energy and leads to a severe fine-tuning, known as the cosmological constant problem. We abandon the standard interpretation that time is a global parameter in quantum mechanics, replace it by a quantum dynamical variable playing the role of an operational quantum clock system. In the framework of reinterpretation of time, we find that the synchronization of two quantum clocks distance apart can not be realized in all rigor at quantum level. Thus leading to an intrinsic quantum uncertainty of simultaneity between spatial interval, which implies a visional vacuum energy fluctuation and gives an observed dark energy density $\\rho_{de}=\\frac{6}{\\pi}L_{P}^{-2}L_{H}^{-2}$, whe...

  15. Hybrid quantum information processing

    Energy Technology Data Exchange (ETDEWEB)

    Furusawa, Akira [Department of Applied Physics, School of Engineering, The University of Tokyo (Japan)

    2014-12-04

    I will briefly explain the definition and advantage of hybrid quantum information processing, which is hybridization of qubit and continuous-variable technologies. The final goal would be realization of universal gate sets both for qubit and continuous-variable quantum information processing with the hybrid technologies. For that purpose, qubit teleportation with a continuousvariable teleporter is one of the most important ingredients.

  16. Bohm's Quantum Potential as an Internal Energy

    OpenAIRE

    Dennis, Glen; De Gosson, Maurice,; Hiley, Basil

    2014-01-01

    We pursue our discussion of Fermi's surface initiated in Dennis, de Gosson and Hiley and show that Bohm's quantum potential can be viewed as an internal energy of a quantum system. This gives further insight into the role it played by the quantum potential in stationary states. It also allows us to provide a physically motivated derivation of Schr\\"odinger's equation for a particle in an external potential.

  17. Entropy and Energy in Quantum Measurement

    Directory of Open Access Journals (Sweden)

    Andreas E. Schlatter

    2006-05-01

    Full Text Available On the basis of the classical axioms of non relativistic quantum mechanics, we develop a model for the interplay between energy and entropy in the process of quantum measurement and shed light on the scope of some of the axioms with regard to the measurement problem.

  18. DIY teleport hats - the consolation of technology

    DEFF Research Database (Denmark)

    Hansen, Lone Koefoed

    2009-01-01

    This instructable describes how to make a set of teleport hats. A teleport hat is a crocheted hat which doubles as a device with which you can teleport yourself to a person wearing the same type of hat in case you miss oneanother and want to be together without the hassle of driving, jetting...

  19. Optimization of the transmission of observable expectation values and observable statistics in Continuous Variable Teleportation

    CERN Document Server

    Farias, L Albano

    2010-01-01

    We analyze the statistics of observables in continuous variable quantum teleportation in the formalism of the characteristic function. We derive expressions for average values of output state observables in particular cumulants which are additive in terms of the input state and the resource of teleportation. Working with Squeezed Bell-like states, which may be optimized in a free parameter for better teleportation performance we discuss the relation between resources optimal for fidelity and for different observable averages. We obtain the values of the free parameter which optimize the central momenta and cumulants up to fourth order. For the cumulants the distortion between in and out states due to teleportation depends only on the resource. We obtain optimal parameters for the second and fourth order cumulants which do not depend on the squeezing of the resource. The second order central momenta which is equal to the second order cumulants and the photon number average are optimized by the same resource. W...

  20. Teleportation of squeezing: Optimization using non-Gaussian resources

    Science.gov (United States)

    Dell'Anno, Fabio; de Siena, Silvio; Adesso, Gerardo; Illuminati, Fabrizio

    2010-12-01

    We study the continuous-variable quantum teleportation of states, statistical moments of observables, and scale parameters such as squeezing. We investigate the problem both in ideal and imperfect Vaidman-Braunstein-Kimble protocol setups. We show how the teleportation fidelity is maximized and the difference between output and input variances is minimized by using suitably optimized entangled resources. Specifically, we consider the teleportation of coherent squeezed states, exploiting squeezed Bell states as entangled resources. This class of non-Gaussian states, introduced by Illuminati and co-workers [F. Dell’Anno, S. De Siena, L. Albano, and F. Illuminati, Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.76.022301 76, 022301 (2007); F. Dell’Anno, S. De Siena, and F. Illuminati, Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.81.012333 81, 012333 (2010)], includes photon-added and photon-subtracted squeezed states as special cases. At variance with the case of entangled Gaussian resources, the use of entangled non-Gaussian squeezed Bell resources allows one to choose different optimization procedures that lead to inequivalent results. Performing two independent optimization procedures, one can either maximize the state teleportation fidelity, or minimize the difference between input and output quadrature variances. The two different procedures are compared depending on the degrees of displacement and squeezing of the input states and on the working conditions in ideal and nonideal setups.

  1. Quantum Monte Carlo for minimum energy structures

    CERN Document Server

    Wagner, Lucas K

    2010-01-01

    We present an efficient method to find minimum energy structures using energy estimates from accurate quantum Monte Carlo calculations. This method involves a stochastic process formed from the stochastic energy estimates from Monte Carlo that can be averaged to find precise structural minima while using inexpensive calculations with moderate statistical uncertainty. We demonstrate the applicability of the algorithm by minimizing the energy of the H2O-OH- complex and showing that the structural minima from quantum Monte Carlo calculations affect the qualitative behavior of the potential energy surface substantially.

  2. Thermal entanglement and teleportation of a thermally mixed entangled state of a Heisenberg chain through a Werner state

    Institute of Scientific and Technical Information of China (English)

    Huang Li-Yuan; Fang Mao-Fa

    2008-01-01

    The thermal entanglement and teleportation of a thermally mixed entangled state of a two-qubit Heisenberg XXX chain under the Dzyaloshinski-Moriya (DM) anisotropic antisymmetric interaction through a noisy quantum channel given by a Werner state is investigated. The dependences of the thermal entanglement of the teleported state on the DM coupling constant, the temperature and the entanglement of the noisy quantum channel are studied in detail for both the ferromagnetic and the antiferromagnetic cases. The result shows that a minimum entanglement of the noisy quantum channel must be provided in order to realize the entanglement teleportation. The values of fidelity of the teleported state are also studied for these two cases. It is found that under certain conditions, we can transfer an initial state with a better fidelity than that for any classical communication protocol.

  3. Probabilistic Teleportation of an Arbitrary Unknown Two-Qubit State via Positive Operator-Valued Measure and Two Non-maximally Entangled States

    Institute of Scientific and Technical Information of China (English)

    WANG Zhang-Yin; WANG Dong; LIU Jun; SHI Shou-Hua

    2006-01-01

    We present a scheme for probabilistically teleporting an arbitrary unknown two-qubit state through a quantum channel made up of two nonidentical non-maximally entangled states. In this scheme, the probabilistic teleportation is realized by using a proper positive operator-valued measure instead of usual projective measurement.

  4. Deterministic teleportation using single-photon entanglement as a resource

    CERN Document Server

    Björk, Gunnar; Andersen, Ulrik L

    2011-01-01

    We outline a proof that teleportation with a single particle is in principle just as reliable as with two particles. We thereby hope to dispel the skepticism surrounding single-photon entanglement as a valid resource in quantum information. A deterministic Bell state analyzer is proposed which uses only classical resources, namely coherent states, a Kerr non-linearity, and a two-level atom.

  5. Scheme for Realizing Probabilistic Teleportation of Bipartite Photonic States via Linear Optical Elements

    Institute of Scientific and Technical Information of China (English)

    DONG Ping; LIN Ji-Cheng; YANG Ming; CAO Zhuo-Liang

    2006-01-01

    We propose a probabilistic scheme for realizing teleportation of bipartite photonic states using linear optical elements where only requires a two-photon Bell state used as quantum channel. It reduces the requirement of the entanglement of quantum channel, but requires an additional photon and an auxiliary maximally entangled photon pair locally.

  6. Scheme for teleportation of unknown single qubit state via continuous variables entangling channel

    Institute of Scientific and Technical Information of China (English)

    Wang Zhong-Jie; Zhang Kan; Fan Chao-Yang

    2010-01-01

    A new scheme for quantum teleportation of single quantum bit state with using continuous variables entangling channel is presented. In our scheme two entangled light fields are employed. An outstanding characteristic of this scheme is that one atomic state is transmitted directly to another atom without using the third atom as the mediate.

  7. Quantum reading under a local energy constraint

    CERN Document Server

    Spedalieri, Gaetana; Mancini, Stefano; Braunstein, Samuel L; Pirandola, Stefano

    2012-01-01

    Nonclassical states of light play a central role in many quantum information protocols. Very recently, their quantum features have been exploited to improve the readout of information from digital memories, modeled as arrays of microscopic beam splitters [S. Pirandola, Phys. Rev. Lett. 106, 090504 (2011)]. In this model of "quantum reading", a nonclassical source of light with Einstein-Podolski-Rosen correlations has been proven to retrieve more information than any classical source. In particular, the quantum-classical comparison has been performed under a global energy constraint, i.e., by fixing the mean total number of photons irradiated over each memory cell. In this paper we provide an alternative analysis which is based on a local energy constraint, meaning that we fix the mean number of photons per signal mode irradiated over the memory cell. Under this assumption, we investigate the critical number of signal modes after which a nonclassical source of light is able to beat any classical source irradia...

  8. Teleportation attack on the QSDC protocol with a random basis and order

    Institute of Scientific and Technical Information of China (English)

    Gao Fei; Wen Qiao-Yan; Zhu Fu-Chen

    2008-01-01

    The quantum secure direct communication(QSDC)protocol with a random basis and order is analysed and an effective attack,i.e.teleportation attack,is presented.An eavesdropper can obtain half of the transmitted secret bits with the help of this special attack.It is shown that quantum teleportation can be employed to weaken the role of the order-rearrangement encryption at least in a certain circumstance.Meanwhile,a possible improvement on this protocol is proposed,which makes it secure against this kind of attack.

  9. Controlled Probabilistic Teleportation of an Unknown Multi-Particle High-Dimensional Entangled State

    Institute of Scientific and Technical Information of China (English)

    SHI Jin; ZHAN You-Bang

    2009-01-01

    We propose a protocol for controlled probabilistic teleportation of an unknown tripartite qutrit entangled state with two partial tripartite qutrit entangled states as the quantum channel. It is found that teleportation associ-ated with the generalized qutrit Bell-basis measurement, the generalized qutrit π-state measurement and the generalized Hadamard operator in three-dimensional Hilbert space. We generalize the protocol for controlled probabilistic telepor-ration of an unknown k-particle qudit entangled state with a multi-particle qudit entangled state and a tripartite qudit entangled state as the quantum channel. We also calculate the classical communication cost required in both cases.

  10. Experimental realization of optimal asymmetric cloning and telecloning via partial teleportation

    CERN Document Server

    Zhao, Z; Zhou, X Q; Chen, Y A; Lu, C Y; Karlsson, A; Pan, J W; Zhao, Zhi; Zhang, An-Ning; Zhou, Xiao-Qi; Chen, Yu-Ao; Lu, Chao-Yang; Karlsson, Anders; Pan, Jian-Wei

    2004-01-01

    We report an experimental realization of both optimal asymmetric cloning and telecloning of single photons by making use of partial teleportation of an unknown state. In the experiment, we demonstrate that, conditioned on the success of partial teleportation of single photons, not only the optimal asymmetric cloning can be accomplished, but also one of two outputs can be transfered to a distant location, realizing the telecloning. The experimental results represented a novel way to achieve the quantum cloning and may have potential applications in the context of quantum cryptography.

  11. Schemes for Probabilistic Teleportation of an Unknown Three-Particle Three-Level Entangled State

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In this paper, two schemes for teleporting an unknown three-particle three-level entangled state are proposed. In the first scheme, two partial three-particle three-level entangled states are used as the quantum channels, while in the second scheme, three two-particle three-level non-maximally entangled states are employed as quantum channels.It is shown that the teleportation can be successfully realized with certain probability, for both two schemes, if a receiver adopts some appropriate unitary transformations. It is shown also that the successful probabilities of these two schemes are different.

  12. Teleportation of a two-atom entangled state using a single EPR pair in cavity QED

    Institute of Scientific and Technical Information of China (English)

    Ji Xin; Li Ke; Zhang Shou

    2006-01-01

    We propose a scheme for teleporting a two-atom entangled state in cavity quantum electrodynamics(QED).In the scheme,we choose a single Einstein-Podolsky-Rosen (EPR) pair as the quantum channel which is shared by the sender and the receiver.By using the atom-cavity-field interaction and introducing an additional atom,we can teleport the two-atom entangled state successfully with a probability of 1.0.Moreover,we show that the scheme is insensitive to cavity decay and thermal field.

  13. Probabilistic Teleportation of an Unknown One-Particle State by a Three-Particle General W State

    Institute of Scientific and Technical Information of China (English)

    XIU Xiao-Ming; DONG Li; GAO Ya-Jun

    2007-01-01

    Two schemes for teleporting an unknown one-particle state are proposed when a general W state is utilized as quantum channel.In the first scheme,after the sender (Alice) makes a Bell-state measurement on her particles,the recipient (Bob) performs a Von Neumann measurement and introduces an auxiliary particle,and carries out a unitary transformation on his particle and the auxiliary particle,and performs a Von Neumann measurement on the auxiliary particle to confirm whether the teleportation succeeds or not.In the second scheme,the recipient (Bob) does not need to perform the first Von Neumann measurement or introduce the auxiliary particle,which is necessary in the first scheme.It is shown that the maximal probabilities of successful teleportation of the two schemes are identical if the recipient (Bob) performs an appropriate unitary transformation and adopts a proper particle on which he recovers the quantum information of state to be teleported.

  14. Quantum mechanical theory behind "dark energy"?

    CERN Multimedia

    Colin Johnson, R

    2007-01-01

    "The mysterious increase in the acceleration of the universe, when intuition says it should be slowing down, is postulated to be caused by dark energy - "dark" because it is undetected. Now a group of scientists in the international collaboration Essence has suggested that a quantum mechanical interpretation of Einstein's proposed "cosmological constant" is the simplest explanation for dark energy. The group measured dark energy to within 10 percent." (1,5 page)

  15. Improving fidelity in atomic state teleportation via cavity decay

    CERN Document Server

    Chimczak, G; Chimczak, Grzegorz; Tana\\'s, Ryszard

    2007-01-01

    We propose a modified protocol of atomic state teleportation for the scheme proposed by Bose et al. (Phys. Rev. Lett. 83, 5158 (1999)). The modified protocol involves an additional stage in which quantum information distorted during the first stage is fully recovered by a compensation of the damping factor. The modification makes it possible to obtain a high fidelity of teleported state for cavities that are much worse than that required in the original protocol, i.e., their decay rates can be over 25 times larger. The improvement in the fidelity is possible at the expense of lowering the probability of success. We show that the modified protocol is robust against dark counts.

  16. Probabilistic teleportation of a non-symmetric three-particle state

    Institute of Scientific and Technical Information of China (English)

    Chen Xiu-Bo; Wen Qiao-Yan; Zhu Fu-Chen

    2006-01-01

    This paper proposes a scheme for teleporting a kind of essential three-particle non-symmetric entangled state,which is much more valuable than a GHZ and W state for some applications in quantum information processing. In comparison with previous proposal of teleportation, the resources of entangled states as quantum channel and the number of classical messages required by our scheme can be cut down. Moreover, it is shown that there exists a class of transformations which ensure the success of this scheme, because the two-particle transformation performed by the receiver in the course of teleportation may be a generic two-particle operation instead of a control-NOT (CNOT) operation. In addition, all kinds of transformations performed by sender and receiver are given in detail.

  17. DIY teleport hats - the consolation of technology

    DEFF Research Database (Denmark)

    Hansen, Lone Koefoed

    2009-01-01

    This instructable describes how to make a set of teleport hats. A teleport hat is a crocheted hat which doubles as a device with which you can teleport yourself to a person wearing the same type of hat in case you miss oneanother and want to be together without the hassle of driving, jetting or b...... but it works well as a gift for someone you miss or someone who misses another person madly as it provides an opportunity to take some kind of action when ordinary options like driving, jetting or biking are not feasible even if the action is only symbolic.......This instructable describes how to make a set of teleport hats. A teleport hat is a crocheted hat which doubles as a device with which you can teleport yourself to a person wearing the same type of hat in case you miss oneanother and want to be together without the hassle of driving, jetting...

  18. The quantum mechanics based on a general kinetic energy

    CERN Document Server

    Wei, Yuchuan

    2016-01-01

    In this paper, we introduce the Schrodinger equation with a general kinetic energy operator. The conservation law is proved and the probability continuity equation is deducted in a general sense. Examples with a Hermitian kinetic energy operator include the standard Schrodinger equation, the relativistic Schrodinger equation, the fractional Schrodinger equation, the Dirac equation, and the deformed Schrodinger equation. We reveal that the Klein-Gordon equation has a hidden non-Hermitian kinetic energy operator. The probability continuity equation with sources indicates that there exists a different way of probability transportation, which is probability teleportation. An average formula is deducted from the relativistic Schrodinger equation, the Dirac equation, and the K-G equation.

  19. Energy transmission using recyclable quantum entanglement

    Science.gov (United States)

    Ye, Ming-Yong; Lin, Xiu-Min

    2016-07-01

    It is known that faster-than-light (FTL) transmission of energy could be achieved if the transmission were considered in the framework of non-relativistic classical mechanics. Here we show that FTL transmission of energy could also be achieved if the transmission were considered in the framework of non-relativistic quantum mechanics. In our transmission protocol a two-spin Heisenberg model is considered and the energy is transmitted by two successive local unitary operations on the initially entangled spins. Our protocol does not mean that FTL transmission can be achieved in reality when the theory of relativity is considered, but it shows that quantum entanglement can be used in a recyclable way in energy transmission.

  20. Quantum scattering at low energies

    DEFF Research Database (Denmark)

    Derezinski, Jan; Skibsted, Erik

    2009-01-01

    For a class of negative slowly decaying potentials, including V(x):=−γ|x|−μ with 0low-energy regime. Using appropriate modifiers of the Isozaki–Kitada type we show that scattering theory is well behaved on the whole continuous spectrum...

  1. Quantum gravity momentum representation and maximum energy

    Science.gov (United States)

    Moffat, J. W.

    2016-11-01

    We use the idea of the symmetry between the spacetime coordinates xμ and the energy-momentum pμ in quantum theory to construct a momentum space quantum gravity geometry with a metric sμν and a curvature tensor Pλ μνρ. For a closed maximally symmetric momentum space with a constant 3-curvature, the volume of the p-space admits a cutoff with an invariant maximum momentum a. A Wheeler-DeWitt-type wave equation is obtained in the momentum space representation. The vacuum energy density and the self-energy of a charged particle are shown to be finite, and modifications of the electromagnetic radiation density and the entropy density of a system of particles occur for high frequencies.

  2. Quantum chromodynamics at high energy

    CERN Document Server

    Kovchegov, Yuri V

    2012-01-01

    Filling a gap in the current literature, this book is the first entirely dedicated to high energy QCD including parton saturation. It presents groundbreaking progress on the subject and describes many of the problems at the forefront of research, bringing postgraduate students, theorists and advanced experimentalists up to date with the current status of the field. A broad range of topics in high energy QCD are covered, most notably on the physics of parton saturation and the Color Glass Condensate (CGC). The material is presented in a pedagogical way, with numerous examples and exercises. Discussion ranges from the quasi-classical McLerran–Venugopalan model to the linear and non-linear BFKL/BK/JIMWLK small-x evolution equations. The authors adopt both a theoretical and experimental outlook and present the physics of strong interactions in a universal way, making it useful to physicists from various sub-communities and applicable to processes studied at high energy accelerators around the world.

  3. Improving the efficiency of single and multiple teleportation protocols based on the direct use of partially entangled states

    Energy Technology Data Exchange (ETDEWEB)

    Fortes, Raphael; Rigolin, Gustavo, E-mail: rigolin@ifi.unicamp.br

    2013-09-15

    We push the limits of the direct use of partially pure entangled states to perform quantum teleportation by presenting several protocols in many different scenarios that achieve the optimal efficiency possible. We review and put in a single formalism the three major strategies known to date that allow one to use partially entangled states for direct quantum teleportation (no distillation strategies permitted) and compare their efficiencies in real world implementations. We show how one can improve the efficiency of many direct teleportation protocols by combining these techniques. We then develop new teleportation protocols employing multipartite partially entangled states. The three techniques are also used here in order to achieve the highest efficiency possible. Finally, we prove the upper bound for the optimal success rate for protocols based on partially entangled Bell states and show that some of the protocols here developed achieve such a bound. -- Highlights: •Optimal direct teleportation protocols using directly partially entangled states. •We put in a single formalism all strategies of direct teleportation. •We extend these techniques for multipartite partially entangle states. •We give upper bounds for the optimal efficiency of these protocols.

  4. Quantum reading under a local energy constraint

    Science.gov (United States)

    Spedalieri, Gaetana; Lupo, Cosmo; Mancini, Stefano; Braunstein, Samuel L.; Pirandola, Stefano

    2012-07-01

    Nonclassical states of light play a central role in many quantum information protocols. Very recently, their quantum features have been exploited to improve the readout of information from digital memories, modeled as arrays of microscopic beam splitters [Pirandola, Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.106.090504 106, 090504 (2011)]. In this model of “quantum reading,” a nonclassical source of light with Einstein-Podolski-Rosen correlations has been proven to retrieve more information than any classical source. In particular, the quantum-classical comparison has been performed under a global energy constraint, i.e., by fixing the mean total number of photons irradiated over each memory cell. In this paper we provide an alternative analysis which is based on a local energy constraint, meaning that we fix the mean number of photons per signal mode irradiated over the memory cell. Under this assumption, we investigate the critical number of signal modes after which a nonclassical source of light is able to beat any classical source irradiating the same number of signals.

  5. Faithfully probabilistic teleportation of an unknown atomic state and cavity field state with a single measurement

    Institute of Scientific and Technical Information of China (English)

    Yang Zhen-Biao; Wu Huai-Zhi; Su Wan-Jun; Zhong Zhi-Rong; Zheng Shi-Biao

    2007-01-01

    This paper shows that, based on the single-photon JC model depicting the resonant interaction of a two-level atom with a single cavity mode, an unknown atomic state and cavity photon superposition state can be faithfully teleported with only a single measurement. The scheme is probabilistic, its success lies on the event that the sender atom (or the medi-atom, for teleportation of cavity field state) is detected in the higher state. The scheme is in contrast to the previous ones of using a maximally two-particle entangled state as quantum channel.

  6. Teleportation of arbitrary unknown two-atom state with Cluster state via thermal cavity

    Institute of Scientific and Technical Information of China (English)

    Zhang Wen; Liu Yi-Min; Liu Jun; Zhang Zhan-Jun

    2008-01-01

    This paper proposes a scheme for implementing the teleportation of an arbitrary unknown two-atom state by using a cluster state of four identical 2-level atoms as quantum channel in a thermal cavity.The two distinct advantages of the present scheme are:(i)The discrimination of 16 orthonormal cluster states in the standard teleportation protocol is transformed into the discrimination of single-atom states.Consequently,the discrimination difficulty of states is degraded.(ii)The scheme is insensitive to the cavity field state and the cavity decay for the thermal cavity is only virtually excited when atoms interact with it.Thus.the scheme is more feasible.

  7. Probabilistic teleportation of a two-particle entangled state via a partially entangled pair

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiu-bo; LIU Xin-yuan; WEN Qiao-yan; ZHU Fu-chen

    2006-01-01

    A scheme for teleporting an unknown two-particle entangled state is proposed. In comparison with the recent protocol (Cola et al., Phys. Lett. A 337 (2005)), the entangled state as quantum channel required by this scheme is a single,partially entangled pair, which is much easier to prepare and maintain. Furthermore, a positive operator valued measure (POVM) is adopted and all kinds of transformations performed by sender and receiver are given in detail. It is shown that the probability of successful teleportation is twice the modulus square of the smaller Schmidt coefficient of the two-particle entangled state, and the fidelity can reach one.

  8. Spin Squeezing and Entanglement with Room Temperature Atoms for Quantum Sensing and Communication

    DEFF Research Database (Denmark)

    Shen, Heng

    magnetometer at room temperature is reported. Furthermore, using spin-squeezing of atomic ensemble, the sensitivity of magnetometer is improved. Deterministic continuous variable teleportation between two distant atomic ensembles is demonstrated. The fidelity of teleportating dynamically changing sequence...... of spin states surpasses a classical benchmark, demonstrating the true quantum teleportation....

  9. 基于隐形传态的网络流量控制研究%Network traffic control based on quantum teleportation2

    Institute of Scientific and Technical Information of China (English)

    胡晓欢; 周小清; 李智伟; 朱聿蔚

    2016-01-01

    Based on the classical channel to facilitate control indirectly to control quantum channel. By setting up two virtual circuit list amended rules:Rule 1 and Rule 2, to control the virtual circuit list. Control of the information flat of quantum channel by recompose virtual circuit list, to control quantum network traffic.%文章通过对经典信道施加控制间接对量子信道进行控制。通过设立两个虚电路列表修改规则:规则1与规则2,控制节点中虚电路列表的添加与删除。通过虚电路列表控制间接控制量子信道的信息发送平率,从而达到对量子网络的流量进行控制。

  10. Energy level statistics of quantum dots.

    Science.gov (United States)

    Tsau, Chien-Yu; Nghiem, Diu; Joynt, Robert; Woods Halley, J

    2007-05-08

    We investigate the charging energy level statistics of disordered interacting electrons in quantum dots by numerical calculations using the Hartree approximation. The aim is to obtain a global picture of the statistics as a function of disorder and interaction strengths. We find Poisson statistics at very strong disorder, Wigner-Dyson statistics for weak disorder and interactions, and a Gaussian intermediate regime. These regimes are as expected from previous studies and fundamental considerations, but we also find interesting and rather broad crossover regimes. In particular, intermediate between the Gaussian and Poisson regimes we find a two-sided exponential distribution for the energy level spacings. In comparing with experiment, we find that this distribution may be realized in some quantum dots.

  11. Energy level statistics of quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Tsau, C-Y [University of Wisconsin-Madison, Madison, WI 53706 (United States); Nghiem, Diu [University of Wisconsin-Madison, Madison, WI 53706 (United States); Joynt, Robert [University of Wisconsin-Madison, Madison, WI 53706 (United States); Halley, J Woods [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States)

    2007-05-08

    We investigate the charging energy level statistics of disordered interacting electrons in quantum dots by numerical calculations using the Hartree approximation. The aim is to obtain a global picture of the statistics as a function of disorder and interaction strengths. We find Poisson statistics at very strong disorder, Wigner-Dyson statistics for weak disorder and interactions, and a Gaussian intermediate regime. These regimes are as expected from previous studies and fundamental considerations, but we also find interesting and rather broad crossover regimes. In particular, intermediate between the Gaussian and Poisson regimes we find a two-sided exponential distribution for the energy level spacings. In comparing with experiment, we find that this distribution may be realized in some quantum dots.

  12. Energy level statistics of quantum dots

    Science.gov (United States)

    Tsau, Chien-Yu; Nghiem, Diu; Joynt, Robert; Halley, J. Woods

    2007-05-01

    We investigate the charging energy level statistics of disordered interacting electrons in quantum dots by numerical calculations using the Hartree approximation. The aim is to obtain a global picture of the statistics as a function of disorder and interaction strengths. We find Poisson statistics at very strong disorder, Wigner-Dyson statistics for weak disorder and interactions, and a Gaussian intermediate regime. These regimes are as expected from previous studies and fundamental considerations, but we also find interesting and rather broad crossover regimes. In particular, intermediate between the Gaussian and Poisson regimes we find a two-sided exponential distribution for the energy level spacings. In comparing with experiment, we find that this distribution may be realized in some quantum dots.

  13. Quantum energy inequalities in two dimensions

    CERN Document Server

    Fewster, C J

    2004-01-01

    Quantum energy inequalities (QEIs) were established by Flanagan for the massless scalar field on two-dimensional Lorentzian spacetimes globally conformal to Minkowski space. We extend his result to all two-dimensional globally hyperbolic Lorentzian spacetimes and use it to show that flat spacetime QEIs give a good approximation to the curved spacetime results on sampling timescales short in comparison with natural geometric scales. This is relevant to the application of QEIs to constrain exotic spacetime metrics.

  14. Quantum energy inequalities in two dimensions

    Science.gov (United States)

    Fewster, Christopher J.

    2004-12-01

    Quantum energy inequalities (QEIs) were established by Flanagan for the massless scalar field on two-dimensional Lorentzian spacetimes globally conformal to Minkowski space. We extend his result to all two-dimensional globally hyperbolic Lorentzian spacetimes and use it to show that flat spacetime QEIs give a good approximation to the curved spacetime results on sampling time scales short in comparison with natural geometric scales. This is relevant to the application of QEIs to constrain exotic spacetime metrics.

  15. Energy loss rate in disordered quantum well

    Energy Technology Data Exchange (ETDEWEB)

    Tripathi, P.; Ashraf, S. S. Z. [Centre of Excellence in Nanomaterials, Faculty of Engineering and Technology, Aligarh Muslim University, Aligarh-202002 (India); Hasan, S. T. [Physics Department, Faculty of Science, The M.S. University of Baroda, Vadodara-390002 (India); Sharma, A. C. [Physics Department, Sibli National College, Azamgarh-276128 (India)

    2014-04-24

    We report the effect of dynamically screened deformation potential on the electron energy loss rate in disordered semiconductor quantum well. Interaction of confined electrons with bulk acoustic phonons has been considered in the deformation coupling. The study concludes that the dynamically screened deformation potential coupling plays a significant role as it substantially affects the power dependency of electron relaxation on temperature and mean free path.

  16. Teleportation of the one-qubit state with environment-disturbed recovery operations

    CERN Document Server

    Hu, Ming-Liang

    2011-01-01

    We study standard protocol $\\mathcal{P}_0$ for teleporting the one-qubit state with both the transmission process of the two qubits constitute the quantum channel and the recovery operations performed by Bob disturbed by the decohering environment. The results revealed that Bob's imperfect operations do not eliminate the possibility of nonclassical teleportation fidelity provided he shares an ideal channel state with Alice, while the transmission process is constrained by a critical time $t_{0,c}$ longer than which will result in failure of $\\mathcal{P}_0$ if the two qubits are corrupted by the decohering environment. Moreover, we found that under the condition of the same decoherence rate $\\gamma$, the teleportation protocol is significantly more fragile when it is executed under the influence of the noisy environment than those under the influence of the dissipative and dephasing environments.

  17. A new representation and probabilistic teleportation of an arbitrary and unknown N-particle state

    Institute of Scientific and Technical Information of China (English)

    Dong Li; Xiu Xiao-Ming; Gao Ya-Jun

    2006-01-01

    A new representation of an arbitrary and unknown N-particle state is presented at first. As an application,a scheme for teleporting an arbitrary and unknown N-particle state is proposed when N pairs of two-particle nonmaximally entangled states are utilized as quantum channels. After Alice (sender) makes Bell-state measurement on her particles, Bob (recipient) introduces an auxiliary particle and carries out appropriate unitary transformation on his particle and the auxiliary particle depending on classical information from Alice. Then, yon Neumann measurement that confirms whether the teleportation succeeds or not is performed by Bob on the auxiliary particle. In order to complete the teleportation, another N-1 times operations need to be performed which are similar to the above ones. It can be successfully realized with a certain probability which is determined by the product of the smaller coefficients of non-maximally entangled pairs. All possible unitary transformations are given in detail.

  18. Approximate calculation of electronic energy levels of axially symmetric quantum dot and quantum ring by using energy dependent effective mass

    Institute of Scientific and Technical Information of China (English)

    Liu Yu-Min; Yu Zhong-Yuan

    2009-01-01

    Calculations of electronic structures about the semiconductor quantum dot and the semiconductor quantum ring are presented in this paper. To reduce the calculation costs, for the quantum dot and the quantum ring, their simplified axially symmetric shapes are utilized in our analysis. The energy dependent effective mass is taken into account in solving the Schrodinger equations in the single band effective mass approximation. The calculated results show that the energy dependent effective mass should be considered only for relatively small volume quantum dots or small quantum rings. For large size quantum materials, both the energy dependent effective mass and the parabolic effective mass can give the same results. The energy states and the effective masses of the quantum dot and the quantum ring as a function of geometric parameters are also discussed in detail.

  19. Probabilistic Teleportation of Three-Atom State via Five-Atom Cluster State

    Institute of Scientific and Technical Information of China (English)

    YU Li-Zhi; WU Tao

    2013-01-01

    A scheme for probabilistic teleportation of an unknown three-atom entangled state via a five-atom nonmaximally entangled duster state as quantum channel is proposed.In this scheme,the sender performs two Bell state and a single-atom measurements on the atoms,the receiver can reconstruct the original state with a certain probability by introducing an auxiliary atom and operating appropriate unitary transformations and controlled-not (C-not) operations according to the sender Alice's measurement results.As a result,the probability of successful teleportation is determined by the smallest two of the coefficients' absolute values of the cluster state.The considerable advantage of our scheme is that we employ a non-maximally entangled cluster state as quantum channel in the scheme,which can greatly reduce the amount of entanglement resources and need less classical bits.If we employ a maximally entangled cluster state as quantum channei,the probabilistic teleportation scheme becomes usual teleportation,the successful probability being 100%.

  20. Highly efficient entanglement swapping and teleportation at telecom wavelength

    Science.gov (United States)

    Jin, Rui-Bo; Takeoka, Masahiro; Takagi, Utako; Shimizu, Ryosuke; Sasaki, Masahide

    2015-03-01

    Entanglement swapping at telecom wavelengths is at the heart of quantum networking in optical fiber infrastructures. Although entanglement swapping has been demonstrated experimentally so far using various types of entangled photon sources both in near-infrared and telecom wavelength regions, the rate of swapping operation has been too low to be applied to practical quantum protocols, due to limited efficiency of entangled photon sources and photon detectors. Here we demonstrate drastic improvement of the efficiency at telecom wavelength by using two ultra-bright entangled photon sources and four highly efficient superconducting nanowire single photon detectors. We have attained a four-fold coincidence count rate of 108 counts per second, which is three orders higher than the previous experiments at telecom wavelengths. A raw (net) visibility in a Hong-Ou-Mandel interference between the two independent entangled sources was 73.3 +/- 1.0% (85.1 +/- 0.8%). We performed the teleportation and entanglement swapping, and obtained a fidelity of 76.3% in the swapping test. Our results on the coincidence count rates are comparable with the ones ever recorded in teleportation/swapping and multi-photon entanglement generation experiments at around 800 nm wavelengths. Our setup opens the way to practical implementation of device-independent quantum key distribution and its distance extension by the entanglement swapping as well as multi-photon entangled state generation in telecom band infrastructures with both space and fiber links.

  1. Highly efficient entanglement swapping and teleportation at telecom wavelength.

    Science.gov (United States)

    Jin, Rui-Bo; Takeoka, Masahiro; Takagi, Utako; Shimizu, Ryosuke; Sasaki, Masahide

    2015-03-20

    Entanglement swapping at telecom wavelengths is at the heart of quantum networking in optical fiber infrastructures. Although entanglement swapping has been demonstrated experimentally so far using various types of entangled photon sources both in near-infrared and telecom wavelength regions, the rate of swapping operation has been too low to be applied to practical quantum protocols, due to limited efficiency of entangled photon sources and photon detectors. Here we demonstrate drastic improvement of the efficiency at telecom wavelength by using two ultra-bright entangled photon sources and four highly efficient superconducting nanowire single photon detectors. We have attained a four-fold coincidence count rate of 108 counts per second, which is three orders higher than the previous experiments at telecom wavelengths. A raw (net) visibility in a Hong-Ou-Mandel interference between the two independent entangled sources was 73.3 ± 1.0% (85.1 ± 0.8%). We performed the teleportation and entanglement swapping, and obtained a fidelity of 76.3% in the swapping test. Our results on the coincidence count rates are comparable with the ones ever recorded in teleportation/swapping and multi-photon entanglement generation experiments at around 800 nm wavelengths. Our setup opens the way to practical implementation of device-independent quantum key distribution and its distance extension by the entanglement swapping as well as multi-photon entangled state generation in telecom band infrastructures with both space and fiber links.

  2. Types of quantum information

    OpenAIRE

    Griffiths, Robert B.

    2007-01-01

    Quantum, in contrast to classical, information theory, allows for different incompatible types (or species) of information which cannot be combined with each other. Distinguishing these incompatible types is useful in understanding the role of the two classical bits in teleportation (or one bit in one-bit teleportation), for discussing decoherence in information-theoretic terms, and for giving a proper definition, in quantum terms, of ``classical information.'' Various examples (some updating...

  3. Biexciton binding energy in ZnSe quantum wells and quantum wires

    DEFF Research Database (Denmark)

    Wagner, Hans-Peter; Langbein, Wolfgang; Hvam, Jørn Märcher

    2002-01-01

    The biexciton binding energy E-XX is investigated in ZnSe/ZnMgSe quantum wells and quantum wires as a function of the lateral confinement by transient four-wave mixing. In the quantum wells one observes for decreasing well width a significant increase in the relative binding energy, saturating...

  4. Probabilistic teleportation of an arbitrary three-particle state via a partial entangled four-particle state and a partial entangled pair

    Institute of Scientific and Technical Information of China (English)

    戴宏毅; 李承祖; 陈平行

    2003-01-01

    We present a scheme to probabilistically teleport an arbitrary and unknown three-particle state via a two-particle non-maximally entangled state and a four-particle non-maximally entangled state as the quantum channel. With the help of Bell-state measurements, an arbitrary three-particle state can be perfectly teleported if a receiver introduces a collective unitary transformation. All kinds of unitary transformations are given in greater detail. This scheme can be generalized to the teleportation of an arbitrary and unknown multiparticle state.

  5. Dark energy from primordial inflationary quantum fluctuations.

    Science.gov (United States)

    Ringeval, Christophe; Suyama, Teruaki; Takahashi, Tomo; Yamaguchi, Masahide; Yokoyama, Shuichiro

    2010-09-17

    We show that current cosmic acceleration can be explained by an almost massless scalar field experiencing quantum fluctuations during primordial inflation. Provided its mass does not exceed the Hubble parameter today, this field has been frozen during the cosmological ages to start dominating the Universe only recently. By using supernovae data, completed with baryonic acoustic oscillations from galaxy surveys and cosmic microwave background anisotropies, we infer the energy scale of primordial inflation to be around a few TeV, which implies a negligible tensor-to-scalar ratio of the primordial fluctuations. Moreover, our model suggests that inflation lasted for an extremely long period. Dark energy could therefore be a natural consequence of cosmic inflation close to the electroweak energy scale.

  6. Quantum Phenomena in High Energy Density Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Murnane, Margaret [Univ. of Colorado, Boulder, CO (United States); Kapteyn, Henry [Univ. of Colorado, Boulder, CO (United States)

    2017-05-10

    The possibility of implementing efficient (phase matched) HHG upconversion of deep- UV lasers in multiply-ionized plasmas, with potentially unprecedented conversion efficiency is a fascinating prospect. HHG results from the extreme nonlinear response of matter to intense laser light:high harmonics are radiated as a result of a quantum coherent electron recollision process that occurs during laser field ionization of an atom. Under current support from this grant in work published in Science in 2015, we discovered a new regime of bright HHG in highly-ionized plasmas driven by intense UV lasers, that generates bright harmonics to photon energies >280eV

  7. Quantum Yang--Mills Dark Energy

    CERN Document Server

    Pasechnik, Roman

    2016-01-01

    In this short review, I discuss basic qualitative characteristics of quantum non-Abelian gauge dynamics in the non-stationary background of the expanding Universe in the framework of the standard Einstein--Yang--Mills formulation. A brief outlook of existing studies of cosmological Yang--Mills fields and their properties will be given. Quantum effects have a profound impact on the gauge field-driven cosmological evolution. In particular, a dynamical formation of the spatially-homogeneous and isotropic gauge field condensate may be responsible for both early and late-time acceleration, as well as for dynamical compensation of non-perturbative quantum vacua contributions to the ground state of the Universe. The main properties of such a condensate in the effective QCD theory at the flat Friedmann--Lema\\'itre--Robertson--Walker (FLRW) background will be discussed within and beyond perturbation theory. Finally, a phenomenologically consistent dark energy can be induced dynamically as a remnant of the QCD vacua co...

  8. Secure quantum communication using classical correlated channel

    Science.gov (United States)

    Costa, D.; de Almeida, N. G.; Villas-Boas, C. J.

    2016-10-01

    We propose a secure protocol to send quantum information from one part to another without a quantum channel. In our protocol, which resembles quantum teleportation, a sender (Alice) and a receiver (Bob) share classical correlated states instead of EPR ones, with Alice performing measurements in two different bases and then communicating her results to Bob through a classical channel. Our secure quantum communication protocol requires the same amount of classical bits as the standard quantum teleportation protocol. In our scheme, as in the usual quantum teleportation protocol, once the classical channel is established in a secure way, a spy (Eve) will never be able to recover the information of the unknown quantum state, even if she is aware of Alice's measurement results. Security, advantages, and limitations of our protocol are discussed and compared with the standard quantum teleportation protocol.

  9. Energy cost of creating quantum coherence

    Science.gov (United States)

    Misra, Avijit; Singh, Uttam; Bhattacharya, Samyadeb; Pati, Arun Kumar

    2016-05-01

    We consider physical situations where the resource theories of coherence and thermodynamics play competing roles. In particular, we study the creation of quantum coherence using unitary operations with limited thermodynamic resources. We find the maximal coherence that can be created under unitary operations starting from a thermal state and find explicitly the unitary transformation that creates the maximal coherence. Since coherence is created by unitary operations starting from a thermal state, it requires some amount of energy. This motivates us to explore the trade-off between the amount of coherence that can be created and the energy cost of the unitary process. We also find the maximal achievable coherence under the constraint on the available energy. Additionally, we compare the maximal coherence and the maximal total correlation that can be created under unitary transformations with the same available energy at our disposal. We find that when maximal coherence is created with limited energy, the total correlation created in the process is upper bounded by the maximal coherence, and vice versa. For two-qubit systems we show that no unitary transformation exists that creates the maximal coherence and maximal total correlation simultaneously with a limited energy cost.

  10. Partial Teleportation of Entanglement Through Natural Thermal Entanglement in Two-Qubit Heisenberg ⅩⅩⅩ Chain

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yong; LONG Gui-Lu; WU Yu-Chun; GUO Guang-Can

    2007-01-01

    Natural thermal entanglement between two qubits with ⅩⅩⅩ Heisenberg interaction is studied. For the antiferromagnet, increasing coupling strength or decreasing temperature under critical point increases the entanglement.Based on the thermal entanglement as quantum channel, entanglement and information of an input entangled state are transferred via partial teleportation. We find that the entanglement transferred will be lost during the process, and for the entanglement fidelity the partial teleportation is superior to classical communication as concurrence of entangled channel beyond 1/4. We show that both correlation information in input entangled state and individual information of the teleported particle are linearly dissipated. With more entanglement in quantum channel, more entanglement and correlation information can be transferred.

  11. Wavelet Scattering Regression of Quantum Chemical Energies

    CERN Document Server

    Hirn, Matthew; Poilvert, Nicolas

    2016-01-01

    We introduce multiscale invariant dictionaries to estimate quantum chemical energies of organic molecules, from training databases. Molecular energies are invariant to isometric atomic displacements, and are Lipschitz continuous to molecular deformations. Similarly to density functional theory (DFT), the molecule is represented by an electronic density function. A multiscale invariant dictionary is calculated with wavelet scattering invariants. It cascades a first wavelet transform which separates scales, with a second wavelet transform which computes interactions across scales. Sparse scattering regressions give state of the art results over two databases of organic planar molecules. On these databases, the regression error is of the order of the error produced by DFT codes, but at a fraction of the computational cost.

  12. Quantum Advantage in Communication Networks

    CERN Document Server

    De, Aditi Sen

    2011-01-01

    Quantum channels are known to provide qualitatively better information transfer capacities over their classical counterparts. Examples include quantum cryptography, quantum dense coding, and quantum teleportation. This is a short review on paradigmatic quantum communication protocols in both bipartite as well as multipartite scenarios.

  13. Quantum hoop conjecture and a natural cutoff for vacuum energy

    CERN Document Server

    Yang, Rong-Jia

    2015-01-01

    We propose here a quantum hoop conjecture which states: the de Broglie wavelength of a quantum system can not be infinitely small, otherwise it will collapse into a quantum black hole. Based on this conjecture, we find an upper bound for the wave number of a particle, which offers a natural cutoff for the vacuum energy.

  14. Teleporting entanglement during black hole evaporation

    Science.gov (United States)

    Brustein, Ram; Medved, A. J. M.

    2016-10-01

    The unitary evaporation of a black hole (BH) in an initially pure state must lead to the eventual purification of the emitted radiation. It follows that the late radiation has to be entangled with the early radiation and, as a consequence, the entanglement among the Hawking pair partners has to decrease continuously from maximal to vanishing during the BH's life span. Starting from the basic premise that both the horizon radius and the center of mass of a finite-mass BH are fluctuating quantum mechanically, we show how this process is realized. First, it is shown that the horizon fluctuations induce a small amount of variance in the total linear momentum of each created pair. This is in contrast to the case of an infinitely massive BH, for which the total momentum of the produced pair vanishes exactly on account of momentum conservation. This variance leads to a random recoil of the BH during each emission and, as a result, the center of mass of the BH undergoes a quantum random walk. Consequently, the uncertainty in its momentum grows as the square root of the number of emissions. We then show that this uncertainty controls the amount of deviation from maximal entanglement of the produced pairs and that this deviation is determined by the ratio of the cumulative number of emitted particles to the initial BH entropy. Thus, the interplay between the horizon and center-of-mass fluctuations provides a mechanism for teleporting entanglement from the pair partners to the BH and the emitted radiation.

  15. Teleporting entanglement during black hole evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Brustein, Ram [Department of Physics, Ben-Gurion University,Beer-Sheva 84105 (Israel); Medved, A.J.M. [Department of Physics & Electronics, Rhodes University,Grahamstown 6140 (South Africa); National Institute for Theoretical Physics (NITheP),Western Cape 7602 (South Africa)

    2016-10-06

    The unitary evaporation of a black hole (BH) in an initially pure state must lead to the eventual purification of the emitted radiation. It follows that the late radiation has to be entangled with the early radiation and, as a consequence, the entanglement among the Hawking pair partners has to decrease continuously from maximal to vanishing during the BH’s life span. Starting from the basic premise that both the horizon radius and the center of mass of a finite-mass BH are fluctuating quantum mechanically, we show how this process is realized. First, it is shown that the horizon fluctuations induce a small amount of variance in the total linear momentum of each created pair. This is in contrast to the case of an infinitely massive BH, for which the total momentum of the produced pair vanishes exactly on account of momentum conservation. This variance leads to a random recoil of the BH during each emission and, as a result, the center of mass of the BH undergoes a quantum random walk. Consequently, the uncertainty in its momentum grows as the square root of the number of emissions. We then show that this uncertainty controls the amount of deviation from maximal entanglement of the produced pairs and that this deviation is determined by the ratio of the cumulative number of emitted particles to the initial BH entropy. Thus, the interplay between the horizon and center-of-mass fluctuations provides a mechanism for teleporting entanglement from the pair partners to the BH and the emitted radiation.

  16. Automated drawing system of quantum energy levels

    Science.gov (United States)

    Stampoultzis, M.; Sinatkas, J.; Tsakstara, V.; Kosmas, T. S.

    2014-03-01

    The purpose of this work is to derive an automated system that provides advantageous drawings of energy spectra for quantum systems (nuclei, atoms, molecules, etc.) required in various physical sciences. The automation involves the development of appropriate computational code and graphical imaging system based on raw data insertion, theoretical calculations and experimental or bibliographic data insertion. The system determines the appropriate scale to depict graphically with the best possible way in the available space. The presently developed code operates locally and the results are displayed on the screen and can be exported to a PostScript file. We note its main features to arrange and visualize in the available space the energy levels with their identity, taking care the existence in the final diagram the least auxiliary deviations. Future improvements can be the use of Java and the availability on the Internet. The work involves the automated plotting of energy levels in molecules, atoms, nuclei and other types of quantized energy spectra. The automation involves the development of an appropriate computational code and graphical imaging system.

  17. Averaged null energy condition in Loop Quantum Cosmology

    CERN Document Server

    Li, Li-Fang

    2008-01-01

    Wormhole and time machine are very interesting objects in general relativity. However, they need exotic matters which are impossible in classical level to support them. But if we introduce the quantum effects of gravity into the stress-energy tensor, these peculiar objects can be constructed self-consistently. Fortunately, loop quantum cosmology (LQC) has the potential to serve as a bridge connecting the classical theory and quantum gravity. Therefore it provides a simple way for the study of quantum effect in the semiclassical case. As is well known, loop quantum cosmology is very successful to deal with the behavior of early universe. In the early stage, if taken the quantum effect into consideration, inflation is natural because of the violation of every kind of local energy conditions. Similar to the inflationary universe, the violation of the averaged null energy condition is the necessary condition for the traversable wormholes. In this paper, we investigate the averaged null energy condition in LQC in ...

  18. Expected number of quantum channels in quantum networks

    Science.gov (United States)

    Chen, Xi; Wang, He-Ming; Ji, Dan-Tong; Mu, Liang-Zhu; Fan, Heng

    2015-07-01

    Quantum communication between nodes in quantum networks plays an important role in quantum information processing. Here, we proposed the use of the expected number of quantum channels as a measure of the efficiency of quantum communication for quantum networks. This measure quantified the amount of quantum information that can be teleported between nodes in a quantum network, which differs from classical case in that the quantum channels will be consumed if teleportation is performed. We further demonstrated that the expected number of quantum channels represents local correlations depicted by effective circles. Significantly, capacity of quantum communication of quantum networks quantified by ENQC is independent of distance for the communicating nodes, if the effective circles of communication nodes are not overlapped. The expected number of quantum channels can be enhanced through transformations of the lattice configurations of quantum networks via entanglement swapping. Our results can shed lights on the study of quantum communication in quantum networks.

  19. Deep Wavelet Scattering for Quantum Energy Regression

    Science.gov (United States)

    Hirn, Matthew

    Physical functionals are usually computed as solutions of variational problems or from solutions of partial differential equations, which may require huge computations for complex systems. Quantum chemistry calculations of ground state molecular energies is such an example. Indeed, if x is a quantum molecular state, then the ground state energy E0 (x) is the minimum eigenvalue solution of the time independent Schrödinger Equation, which is computationally intensive for large systems. Machine learning algorithms do not simulate the physical system but estimate solutions by interpolating values provided by a training set of known examples {(xi ,E0 (xi) } i physical invariants. Linear regressions of E0 over a dictionary Φ ={ϕk } k compute an approximation E 0 as: E 0 (x) =∑kwkϕk (x) , where the weights {wk } k are selected to minimize the error between E0 and E 0 on the training set. The key to such a regression approach then lies in the design of the dictionary Φ. It must be intricate enough to capture the essential variability of E0 (x) over the molecular states x of interest, while simple enough so that evaluation of Φ (x) is significantly less intensive than a direct quantum mechanical computation (or approximation) of E0 (x) . In this talk we present a novel dictionary Φ for the regression of quantum mechanical energies based on the scattering transform of an intermediate, approximate electron density representation ρx of the state x. The scattering transform has the architecture of a deep convolutional network, composed of an alternating sequence of linear filters and nonlinear maps. Whereas in many deep learning tasks the linear filters are learned from the training data, here the physical properties of E0 (invariance to isometric transformations of the state x, stable to deformations of x) are leveraged to design a collection of linear filters ρx *ψλ for an appropriate wavelet ψ. These linear filters are composed with the nonlinear modulus

  20. Classical kinetic energy, quantum fluctuation terms and kinetic-energy functionals

    OpenAIRE

    Hamilton, I. P.; Mosna, Ricardo A.; Site, L. Delle

    2006-01-01

    We employ a recently formulated dequantization procedure to obtain an exact expression for the kinetic energy which is applicable to all kinetic-energy functionals. We express the kinetic energy of an N-electron system as the sum of an N-electron classical kinetic energy and an N-electron purely quantum kinetic energy arising from the quantum fluctuations that turn the classical momentum into the quantum momentum. This leads to an interesting analogy with Nelson's stochastic approach to quant...

  1. Conditionally Teleported States Using Optical Squeezers and Photon Counting

    Institute of Scientific and Technical Information of China (English)

    FAN Hong-Yi; FAN Yue; CHENG Hai-Ling

    2002-01-01

    By virtue of the neat expression of the two-mode squeezing operator in the Einstein,Podolsky and Rosen entangled state representation,we provide a new approach for discussing the teleportation scheme using optical squeezers and photon counting devices.We derive the explicit form of the teleported states,so that the conditional property of teleportation and teleportation fidelity of this protocol can be scen more clcarly.The derivation is concise.

  2. Quantum Information Technology: Entanglement, Teleportation, and Memory

    Science.gov (United States)

    2005-10-31

    International Conference on Squeezed States and Uncertainty Relations (ICSSUR�), Puebla , Mexico, June 9-13, 2003. X. Li, P. Voss, J E. Sharping...the original vision of a dual-OPA entanglement source [2]. The source output thus ob- tained exhibited collapses and revivals of the Hong-Ou-Mandel

  3. Disentanglement, Bell-nonlocality violation and teleportation capacity of the decaying tripartite states

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Ming-Liang, E-mail: mingliang0301@163.com

    2012-09-15

    Dynamics of disentanglement as measured by the tripartite negativity and Bell nonlocality as measured by the extent of violation of the multipartite Bell-type inequalities are investigated in this work. It is shown definitively that for the initial three-qubit Greenberger-Horne-Zeilinger (GHZ) or W class state preparation, the Bell nonlocality suffers sudden death under the influence of thermal reservoirs. Moreover, all the Bell-nonlocal states are useful for nonclassical teleportation, while there are entangled states that do not violate any Bell-type inequalities, but still yield nonclassical teleportation fidelity. - Highlights: Black-Right-Pointing-Pointer Comparison of different aspects of quantum correlations. Black-Right-Pointing-Pointer Robustness of the initial tripartite GHZ and W class states against decoherence. Black-Right-Pointing-Pointer Bell-nonlocality sudden death under the influence of thermal reservoir. Black-Right-Pointing-Pointer A nonzero minimum tripartite negativity is needed for nonclassical teleportation. Black-Right-Pointing-Pointer All the Bell-nonlocal states yield nonclassical teleportation fidelity.

  4. Light harvesting for quantum solar energy conversion

    Science.gov (United States)

    Markvart, Tomas

    2000-05-01

    Despite wide structural and functional differences, the laws that govern quantum solar energy conversion to chemical energy or electricity share many similarities. In the photosynthetic membrane, in common with semiconductor solar cells, the conversion process proceeds from the creation of electron-hole pairs by a photon of light, followed by charge separation to produce the required high-energy product. In many cases, however, mechanisms are needed to enhance the optical absorption cross-section and extend the spectral range of operation. A common way of achieving this is by light harvesting: light absorption by a specialised unit which transfers the energy to the conversion apparatus. This paper considers two examples of light harvesting - semiconductor solar cells and the photosynthetic apparatus - to illustrate the basic operation and principles that apply. The existence of a light harvesting unit in photosynthesis has been known since the early 1930's but details of the process - relating, in particular, to the relationship between the structure and spectral properties - are still being unravelled. The excitation energy carriers are excitons but the precise nature of the transport - via the solid state Frenkel-Peierls variety or by Förster's resonant energy transfer - is still subject to debate. In semiconductor solar cells, the energy of the absorbed photon is collected by minority carriers but the broad principles remain the same. In both cases it is shown that the rate of energy conversion is described by a law which parallels the Shockley's solar cell equation, and the light harvesting energy collection is subject to reciprocity relations which resemble Onsager's reciprocity relations between coefficients which couple appropriate forces and flows in non-equilibrium thermodynamics. Differences in the basic atomic make-up in the two systems lead to different energy transport equations. In both cases, however, similar mathematical techniques based on Green

  5. Remote control of restricted sets of operations Teleportation of Angles

    CERN Document Server

    Huelga, S F; Vaccaro, J A

    2002-01-01

    We study the remote implementation of a unitary transformation on a qubit. We show the existence of non-trivial protocols (i.e., using less resources than bidirectional state teleportation) which allow the perfect remote implementation of certain continuous sets of quantum operations. We prove that, up to a local change of basis, only two subsets exist that can be implemented remotely with a non-trivial protocol: Arbitrary rotations around a fixed direction $\\vec{n}$ and rotations by a fixed angle around an arbitrary direction lying in a plane orthogonal to $\\vec{n}$. The overall classical information and distributed entanglement cost required for the remote implementation depends on whether it is a priori known to which of the two teleportable subsets the transformation belongs to. If it is so, the optimal protocol consumes one e-bit of entanglement and one c-bit in each direction. If the subset is not known, two e-bits of entanglement need to be consumed while the classical channel becomes asymmetric, two c...

  6. Environment-assisted quantum walks in excitonic energy transport

    Science.gov (United States)

    Mohseni, Masoud; Rebentrost, Patrick; Lloyd, Seth; Aspuru-Guzik, Alan

    2010-03-01

    Long-lived quantum coherence has recently been observed experimentally via ultrafast nonlinear spectroscopy in excitonic energy transfer within light-harvesting photosynthetic complexes, conjugated polymers, and marine alga even at room temperature. Here, we demonstrate that directed quantum walks lead to an enhancement of energy transfer efficiency in such systems. We introduce two complementary theoretical approaches, based on a Green's function method and energy transfer susceptibilities, to partition open quantum dynamics. We quantify the role of fundamental physical processes involved in energy transport. In particular, we examine the contributions of classical hopping, coherent excitonic Hamiltonian, and phonon-induced decoherence effects for pure dephasing, Markovian, and non-Markovian limits.

  7. Schemes for Probabilistic Teleportation of a Three-Atom GHZ Class State via Cavity QED

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Using a quantum channel composed of a two-atom and a three-atom nonmaximally entangled states,we present two schemes to teleport a three-atom GHZ class state via entanglement swapping in cavity QED with different success probabilities. The schemes can be respectively realized with the large-detuned vacuum cavities and with the large-detuned thermal cavities by separate atomic measurements after we choose appropriate atom-cavity-field interaction time.

  8. Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers

    Institute of Scientific and Technical Information of China (English)

    LIU Yu-ling; MAN Zhong-xiao; XIA Yun-jie

    2008-01-01

    A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.

  9. The Application of Quantum Energy Saver on Engine

    Directory of Open Access Journals (Sweden)

    Fang Xiong

    2016-01-01

    Full Text Available In order to reduce diesel fuel consumption, this paper conducts the research in view of a new type of quantum energy saving device, and then produce the sample and applied on automobile engine, Detect fuel use of an automobile by automobile fuel saving technology as-sessment methods from the department of transportation. Compare the changes of fuel use be-fore and after installation of quantum energy saving device on the same car, and give the feed-back of energy saving capability. The result shows, after installed quantum energy saver, both fuel consumption and the smoke of tail gas has decreased. The analysis and application of this paper carry out the conclusion that the quantum energy saver can play an important role in en-ergy saving and emission reduction, and provide a reference for other related research.

  10. Effects of Dzyaloshinski-Moriya interaction and intrinsic decoherence on teleportation via a two-qubit Heisenberg XYZ model

    Institute of Scientific and Technical Information of China (English)

    Hu Xiao-Mian; Liu Jin-Ming

    2009-01-01

    Quantum teleportation via the entangled channel composed of a two-qubit Heisenberg XYZ model with Dzyaloshinski-Moriya (DM) interaction in the presence of intrinsic decoherenee has been investigated. We find that the initial state of the channel plays an important role in the teleported state and the average fidelity of teleportation. When the initial channel is in the state [ψ1(0)>=a|00> + b|11>, the average fidelity is equal to 1/3 constantly, which is independent of the DM interaction and the intrinsic decoherence effect. But when the channel is initially in the state [ψ2(0)> = c|01) + d|10>, the average fidelity is always larger than 2/3. Moreover, under a certain condition, the average fidelity can be enhanced by adjusting the DM interaction, and the intrinsic decoherence leads to a suppression of the fluctuation of the average fidelity.

  11. Far from equilibrium energy flow in quantum critical systems

    CERN Document Server

    Bhaseen, M J; Lucas, Andrew; Schalm, Koenraad

    2013-01-01

    We investigate far from equilibrium energy transport in strongly coupled quantum critical systems. Combining results from gauge-gravity duality, relativistic hydrodynamics, and quantum field theory, we argue that long-time energy transport occurs via a universal steady-state for any spatial dimensionality. This is described by a boosted thermal state. We determine the transport properties of this emergent steady state, including the average energy flow and its long-time fluctuations.

  12. Maximum Power Output of Quantum Heat Engine with Energy Bath

    CERN Document Server

    Liu, Shengnan

    2016-01-01

    The difference between quantum isoenergetic process and quantum isothermal process comes from the violation of the law of equipartition of energy in the quantum regime. To reveal an important physical meaning of this fact, here we study a special type of quantum heat engine consisting of three processes: isoenergetic, isothermal and adiabatic processes. Therefore, this engine works between the energy and heat baths. Combining two engines of this kind, it is possible to realize the quantum Carnot engine. Furthermore, considering finite velocity of change of the potential shape, here an infinite square well with moving walls, the power output of the engine is discussed. It is found that the efficiency and power output are both closely dependent on the initial and final states of the quantum isothermal process. The performance of the engine cycle is shown to be optimized by control of the occupation probability of the ground state, which is determined by the temperature and the potential width. The relation betw...

  13. Quantum: information theory: technological challenge; Computacion Cuantica: un reto tecnologico

    Energy Technology Data Exchange (ETDEWEB)

    Calixto, M.

    2001-07-01

    The new Quantum Information Theory augurs powerful machines that obey the entangled logic of the subatomic world. Parallelism, entanglement, teleportation, no-cloning and quantum cryptography are typical peculiarities of this novel way of understanding computation. (Author) 24 refs.

  14. Influence of parameters entanglement on the quantum algorithms

    Directory of Open Access Journals (Sweden)

    Alexey V. Kasarkin

    2012-05-01

    Full Text Available The article we consider the influence of parameters entanglement on the quantum algorithms, in particular influence of partial entanglement for quantum teleportation. The simulation results presented in chart form.

  15. Quantum fluctuations in semiconductor quantum dots and their contributions to the self-energy functions of exciton states

    Science.gov (United States)

    Mutygullina, A. A.; Khamadeev, M. A.; Blum, D. O.; Shirdelhavar, A. H.

    2017-06-01

    Influence of quantum fluctuations in a system consisting of a quantum dot and the reservoir of acoustic phonons on processes in which the quantum dot takes part is investigated. Under some conditions this influence is shown to be very strong. We find a contribution from the quantum fluctuations to the self-energy function of the exciton coupled to the quantum dot.

  16. Polaron Energy and Effective Mass in Parabolic Quantum Wells

    Institute of Scientific and Technical Information of China (English)

    WANG Zhi-Ping; LIANG Xi-Xia

    2005-01-01

    @@ The energy and effective mass of a polaron in a parabolic quantum well are studied theoretically by using LLP-like transformations and a variational approach. Numerical results are presented for the polaron energy and effective mass in the GaAs/Al0.3Ga0.7As parabolic quantum well. The results show that the energy and the effective mass of the polaron both have their maxima in the finite parabolic quantum well but decrease monotonously in the infinite parabolic quantum well with the increasing well width. It is verified that the bulk longitudinal optical phonon mode approximation is an adequate formulation for the electron-phonon coupling in parabolic quantum well structures.

  17. Thermodynamics of relativistic quantum fields: extracting energy from gravitational waves

    CERN Document Server

    Bruschi, David Edward

    2016-01-01

    We investigate the quantum thermodynamical properties of localised relativistic quantum fields that can be used as quantum thermal machines. We study the efficiency and power of energy transfer between the classical degrees of freedom, such as the energy input due to motion or to an impinging gravitational wave, and the excitations of the confined quantum field. We find that the efficiency of energy transfer depends dramatically on the input initial state of the system. Furthermore, we investigate the ability to extract the energy and to store it in a battery. This process is inefficient in optical cavities but is significantly enhanced when employing trapped Bose Einstein Condensates. Finally, we apply our techniques to a setup where an impinging gravitational wave excites the phononic modes of a Bose Einstein Condensate. We find that, in this case, the amount of energy transfer to the phonons increases with time and quickly approaches unity. These results suggest that, in the future, it might be possible to...

  18. Application of Quantum Process Calculus to Higher Dimensional Quantum Protocols

    Directory of Open Access Journals (Sweden)

    Simon J. Gay

    2014-07-01

    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. We have extended the quantum process calculus to describe d-dimensional quantum systems, which has not been done before. We summarise the necessary theory in the generalisation of quantum gates and Bell states and use the theory to apply the quantum process calculus CQP to quantum protocols, namely qudit teleportation and superdense coding.

  19. Quantum Computing

    CERN Document Server

    Steane, A M

    1998-01-01

    The subject of quantum computing brings together ideas from classical information theory, computer science, and quantum physics. This review aims to summarise not just quantum computing, but the whole subject of quantum information theory. It turns out that information theory and quantum mechanics fit together very well. In order to explain their relationship, the review begins with an introduction to classical information theory and computer science, including Shannon's theorem, error correcting codes, Turing machines and computational complexity. The principles of quantum mechanics are then outlined, and the EPR experiment described. The EPR-Bell correlations, and quantum entanglement in general, form the essential new ingredient which distinguishes quantum from classical information theory, and, arguably, quantum from classical physics. Basic quantum information ideas are described, including key distribution, teleportation, data compression, quantum error correction, the universal quantum computer and qua...

  20. Effects of Dirac's Negative Energy Sea on Quantum Numbers

    OpenAIRE

    Jackiw, R.

    1999-01-01

    One route towards understanding both fractional charges and chiral anomalies delves into Dirac's negative energy sea. Usually we think of Dirac's negative energy sea as an unphysical construct, invented to render quantum field theory physically acceptable by hiding the negative energy solutions. I suggest that in fact physical consequences can be drawn from Dirac's construction.

  1. Quantum-Confinement Effects on Binding Energies and Optical Properties of Excitons in Quantum Dots

    Institute of Scientific and Technical Information of China (English)

    潘晖

    2004-01-01

    Quantum-confinement effects on the binding energy and the linear optical susceptibility of excitons in quantum dots are studied. It is found that the binding energy and the linear optical susceptibility are sensitive to the barrier height and the dot size. For an infinite barrier, the binding energy of excitons decreases monotonically with the increasing dot radius, and the absorption intensity has almost the same amplitude with the increasing photon energy. For a finite barrier, the binding energy has a maximum value with the increasing dot radius, and the absorption intensity damps rapidly with the increasing photon energy. The effective mass ratio is also found to have an influence on the binding energy. The results could be confirmed by future experiments on excitons in quantum dots.

  2. Teleportation of a ququart system using hyperentangled photons assisted by atomic-ensemble memories

    Science.gov (United States)

    Luo, Ming-Xing; Li, Hui-Ran; Lai, Hong; Wang, Xiaojun

    2016-01-01

    A single photon encoded in both the spin and the orbital angular momentum has recently been experimentally demonstrated [X.-L. Wang et al., Nature 518, 516 (2015)], 10.1038/nature14246 with linear optics using the hyperentangled state, which can be viewed as a bipartite four-dimensional (ququart) entanglement. Here, we investigate this process from a general point of view. By exploring a controlled phase flip induced by atomic ensembles in one-side optical microcavities, we propose teleportations of general ququart systems including a two-atomic-ensemble system, a two-polarized-photon system, one photon with the polarization and spatial degrees of freedom (DOFs), and a hybrid photon-ensemble system using two hyperentangled photons. The output information may also be encoded by different physical systems up to the special requirements of a receiver. These schemes are also adapted to teleportation of a ququart system with only phases or real probability amplitudes, which is beyond previous superdense teleportation [Nature Commun. 6, 7185 (2015)], 10.1038/ncomms8185. With these restrictions, half of the classical communication cost may be saved and experimental complexities are also reduced. Our theoretical schemes are feasible in modern physics and show the possibilities of transferring complex quantum systems for scalable quantum applications.

  3. Teleportation of an Arbitrary Multipartite GHZ-Class State by One EPR Pair

    Institute of Scientific and Technical Information of China (English)

    WANG Ya-Hong; YU Chang-Shui; SONG He-Shan

    2006-01-01

    We present a scheme for perfectly teleporting an arbitrary and unknown N-particle GHZ-class state from a sender to a receiver. We just need one quantum channel composed of two or three particles in the maximally entangled state. The sender performs one Bell-state measurement on two of her particles and N - 1 Hadamard operations and N- 1 von Neumann measurements on the rest N- 1 particles. The receiver adopts one corresponding unitary transformation on his particles shared with the sender. After that, the receiver can obtain the original N-particle GHZ-class state by introducing N - 1 ancillary particles and carrying out N - 1 controlled-NOT operations. We also generalize the scheme to the case of controlled teleportation.

  4. Quantum-biological control of energy transfer in hybrid quantum dot-metallic nanoparticle systems

    Science.gov (United States)

    Sadeghi, Seyed M.; Hood, Brady; Patty, Kira

    2016-09-01

    We show theoretically that when a semiconductor quantum dot and metallic nanoparticle system interacts with a laser field, quantum coherence can introduce a new landscape for the dynamics of Forster resonance energy transfer (FRET). We predict adsorption of biological molecules to such a hybrid system can trigger dramatic changes in the way energy is transferred, blocking FRET while the distance between the quantum dot and metallic nanoparticle (R) and other structural specifications remain unchanged. We study the impact of variation of R on the FRET rate in the presence of quantum coherence and its ultrafast decay, offering a characteristically different dependency than the standard 1/R6. Application of the results for quantum nanosensors is discussed.

  5. Bibliographic guide to the foundations of quantum mechanics and quantum information

    CERN Document Server

    Cabello, A

    2000-01-01

    This is a collection of references (papers, books, preprints, book reviews, Ph. D. thesis, patents, etc.), sorted alphabetically and (some of them) classified by subject, on foundations of quantum mechanics and quantum information. Specifically, it covers hidden variables (``no-go'' theorems, experiments), interpretations of quantum mechanics, entanglement, quantum effects (quantum Zeno effect, quantum erasure, ``interaction-free'' measurements, quantum ``non-demolition'' measurements), quantum information (cryptography, cloning, dense coding, teleportation), and quantum computation.

  6. Quantum Entropy and Its Applications to Quantum Communication and Statistical Physics

    Directory of Open Access Journals (Sweden)

    Masanori Ohya

    2010-05-01

    Full Text Available Quantum entropy is a fundamental concept for quantum information recently developed in various directions. We will review the mathematical aspects of quantum entropy (entropies and discuss some applications to quantum communication, statistical physics. All topics taken here are somehow related to the quantum entropy that the present authors have been studied. Many other fields recently developed in quantum information theory, such as quantum algorithm, quantum teleportation, quantum cryptography, etc., are totally discussed in the book (reference number 60.

  7. Storage of energy in confined quantum systems

    OpenAIRE

    Malbouisson, A. P. C.

    2002-01-01

    Using the non-perturbative method of {\\it dressed} states introduced in previous publications [N.P.Andion, A.P.C. Malbouisson and A. Mattos Neto, J.Phys.{\\bf A34}, 3735, (2001); G. Flores-Hidalgo, A.P.C. Malbouisson, Y.W. Milla, Phys. Rev. A, {\\bf 65}, 063314 (2002)], we study the evolution of a confined quantum mechanical system embedded in a {\\it ohmic} environment. Our approach furnishes a theoretical mechanism to control inhibition of the decay of excited quantum systems in cavities, in b...

  8. Quantum Computing Resource Estimate of Molecular Energy Simulation

    CERN Document Server

    Whitfield, James D; Aspuru-Guzik, Alán

    2010-01-01

    Over the last century, ingenious physical and mathematical insights paired with rapidly advancing technology have allowed the field of quantum chemistry to advance dramatically. However, efficient methods for the exact simulation of quantum systems on classical computers do not exist. The present paper reports an extension of one of the authors' previous work [Aspuru-Guzik et al., Science {309} p. 1704, (2005)] where it was shown that the chemical Hamiltonian can be efficiently simulated using a quantum computer. In particular, we report in detail how a set of molecular integrals can be used to create a quantum circuit that allows the energy of a molecular system with fixed nuclear geometry to be extracted using the phase estimation algorithm proposed by Abrams and Lloyd [Phys. Rev. Lett. {83} p. 5165, (1999)]. We extend several known results related to this idea and present numerical examples of the state preparation procedure required in the algorithm. With future quantum devices in mind, we provide a compl...

  9. An algorithm for minimization of quantum cost

    OpenAIRE

    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.

  10. Probabilistic Teleportation of an Arbitrary Two-particle State

    Institute of Scientific and Technical Information of China (English)

    顾永建; 郑亦庄; 郭光灿

    2001-01-01

    A scheme for the teleportation of an arbitrary two-particle state via two non-maximally entangled particle pairsis proposed. We show that teleportation can be successfully realized with a certain probability if the receiveradopts an appropriate unitary-reduction strategy. A specific strategy is provided in detail The probability of successful teleportation is determined by the smaller coefficients of the two entangled pairs.

  11. High-energy limit of quantum electrodynamics beyond Sudakov approximation

    Directory of Open Access Journals (Sweden)

    Alexander A. Penin

    2015-05-01

    Full Text Available We study the high-energy behavior of the scattering amplitudes in quantum electrodynamics beyond the leading order of the small electron mass expansion in the leading logarithmic approximation. In contrast to the Sudakov logarithms, the mass-suppressed double-logarithmic radiative corrections are induced by a soft electron pair exchange and result in enhancement of the power-suppressed contribution, which dominates the amplitudes at extremely high energies. Possible applications of our result to the analysis of the high-energy processes in quantum chromodynamics is also discussed.

  12. High-energy limit of quantum electrodynamics beyond Sudakov approximation

    Energy Technology Data Exchange (ETDEWEB)

    Penin, Alexander A., E-mail: penin@ualberta.ca [Department of Physics, University of Alberta, Edmonton, Alberta T6G 2J1 (Canada); Institut für Theoretische Teilchenphysik, Karlsruhe Institute of Technology, 76128 Karlsruhe (Germany)

    2015-05-18

    We study the high-energy behavior of the scattering amplitudes in quantum electrodynamics beyond the leading order of the small electron mass expansion in the leading logarithmic approximation. In contrast to the Sudakov logarithms, the mass-suppressed double-logarithmic radiative corrections are induced by a soft electron pair exchange and result in enhancement of the power-suppressed contribution, which dominates the amplitudes at extremely high energies. Possible applications of our result to the analysis of the high-energy processes in quantum chromodynamics is also discussed.

  13. Energy Emission by Quantum Systems in an Expanding FRW Metric

    CERN Document Server

    Sheehan, D P

    2004-01-01

    Bound quantum mechanical systems not expanding with the comoving frame of an expanding, flat FRW metric are found to release energy at a rate linearly proportional to the local Hubble constant ($H_{o}$) and the systems' binding energy ($E_{b}$); {\\em i.e.}, $\\dot{E} = H_{o} E_{b}$. Three exemplary quantum systems are examined. For systems with early cosmological condensation times | notably hadrons | time-integrated energy release could have been significant and could account for an appreciable fraction of the dark matter inventory.

  14. Quantum energy inequalities and local covariance II: categorical formulation

    Science.gov (United States)

    Fewster, Christopher J.

    2007-11-01

    We formulate quantum energy inequalities (QEIs) in the framework of locally covariant quantum field theory developed by Brunetti, Fredenhagen and Verch, which is based on notions taken from category theory. This leads to a new viewpoint on the QEIs, and also to the identification of a new structural property of locally covariant quantum field theory, which we call local physical equivalence. Covariant formulations of the numerical range and spectrum of locally covariant fields are given and investigated, and a new algebra of fields is identified, in which fields are treated independently of their realisation on particular spacetimes and manifestly covariant versions of the functional calculus may be formulated.

  15. Quantum effects at low-energy atom–molecule interface

    Indian Academy of Sciences (India)

    B Deb; A Rakshit; J Hazra; D Chakraborty

    2013-01-01

    The effects of quantum interference in inter-conversion between cold atoms and diatomic molecules are analysed in this study. Within the framework of Fano’s theory, continuum bound anisotropic dressed state formalism of atom–molecule quantum dynamics is presented. This formalism is applicable in photo- and magneto-associative strong-coupling regimes. The significance of Fano effect in ultracold atom–molecule transitions is discussed. Quantum effects at low-energy atom–molecule interface are important for exploring coherent phenomena in hitherto unexplored parameter regimes.

  16. Teleportation of an arbitrary mixture of diagonal states of multiqudit

    Institute of Scientific and Technical Information of China (English)

    Du Qian-Hua; Lin Xiu-Min; Chen Zhi-Hua; Lin Gong-Wei; Chen Li-Bo; Gu Yong-Jian

    2008-01-01

    This paper proposes a scheme to teleport an arbitrary mixture of diagonal states of multiqutrit via classical correlation and classical communication. To teleport an arbitrary mixture of diagonal states of N qutrits, N classically correlated pairs of two qutrits are used as channel. The sender (Alice) makes Fourier transform and conditional gate (i.e., XOR(3) gate) on her qutrits and does measurement in appropriate computation bases. Then she sends N ctrits to the receiver (Bob). Based on the received information, Bob performs the corresponding unitary transformation on his qutrits and obtains the teleported state. Teleportation of an arbitrary mixture of diagonal states of multiqudit is also discussed.

  17. Teleportation with Tripartite Entangled State via Thermal Cavity

    Institute of Scientific and Technical Information of China (English)

    XUE Zheng-Yuan; YI You-Min; CAO Zhuo-Liang

    2006-01-01

    Teleportation schemes with a tripartite entangled state in cavity QED are investigated. The schemes do not need Bell state measurements and the successful probabilities reach optimality. In addition, the schemes are insensitive to both the cavity decay and the thermal field. We first consider two teleportation schemes via a tripartite GHZ state.The first one is a controlled one for an unknown single-qubit state. The second scheme is teleportation of unknown two-atom entangled state. Then we consider teleporting of single-qubit arbitrary state via a tripartite W state.

  18. Low-Energy Effective Theories of Quantum Link and Quantum Spin Models

    CERN Document Server

    Schlittgen, B

    2001-01-01

    Quantum spin and quantum link models provide an unconventional regularization of field theory in which classical fields arise via dimensional reduction of discrete variables. This D-theory regularization leads to the same continuum theories as the conventional approach. We show this by deriving the low-energy effective Lagrangians of D-theory models using coherent state path integral techniques. We illustrate our method for the $(2+1)$-d Heisenberg quantum spin model which is the D-theory regularization of the 2-d O(3) model. Similarly, we prove that in the continuum limit a $(2+1)$-d quantum spin model with $SU(N)_L\\times SU(N)_R\\times U(1)_{L=R}$ symmetry is equivalent to the 2-d principal chiral model. Finally, we show that $(4+1)$-d SU(N) quantum link models reduce to ordinary 4-d Yang-Mills theory.

  19. Bohm's quantum potential as an internal energy

    Energy Technology Data Exchange (ETDEWEB)

    Dennis, Glen, E-mail: gdennis502@gmail.com [TPRU, Birkbeck College, University of London, London, WC1E 7HX (United Kingdom); Gosson, Maurice A. de, E-mail: maurice.de.gosson@univie.ac.at [University of Vienna, Faculty of Mathematics, NuHAG, Oskar-Morgenstern-Platz 1, 1090 Vienna (Austria); Hiley, Basil J., E-mail: b.hiley@bbk.ac.uk [TPRU, Birkbeck College, University of London, London, WC1E 7HX (United Kingdom)

    2015-06-26

    Highlights: • The quantum potential is seen as internal energy associated with a phase space region. • Fermi's trick shows that Bohm's particle is an extended structure in phase space. • We associate Bohm's quantum potential with a context-dependent energy redistribution. • A physically motivated derivation of Schrodinger's equation is provided. • We show the Fermi set associated with a 3-D coherent state contains a quantum blob. - Abstract: We pursue our discussion of Fermi's surface initiated by Dennis, de Gosson and Hiley and show that Bohm's quantum potential can be viewed as an internal energy of a quantum system, giving further insight into its role in stationary states. This implies that the ‘particle’ referred to in Bohm's theory is not a classical point-like object but rather has an extended structure in phase space which can be linked to the notion of a symplectic capacity, a topological feature of the underlying symplectic geometry. This structure provides us with a new, physically motivated derivation of Schrödinger's equation provided we interpret Gleason's theorem as a derivation of the Born rule from fundamental assumptions about quantum probabilities.

  20. Strained quantum well photovoltaic energy converter

    Science.gov (United States)

    Freundlich, Alexandre (Inventor); Renaud, Philippe (Inventor); Vilela, Mauro Francisco (Inventor); Bensaoula, Abdelhak (Inventor)

    1998-01-01

    An indium phosphide photovoltaic cell is provided where one or more quantum wells are introduced between the conventional p-conductivity and n-conductivity indium phosphide layer. The approach allows the cell to convert the light over a wider range of wavelengths than a conventional single junction cell and in particular convert efficiently transparency losses of the indium phosphide conventional cell. The approach hence may be used to increase the cell current output. A method of fabrication of photovoltaic devices is provided where ternary InAsP and InGaAs alloys are used as well material in the quantum well region and results in an increase of the cell current output.

  1. Quantum grow--a quantum dynamics sampling approach for growing potential energy surfaces and nonadiabatic couplings.

    Science.gov (United States)

    Godsi, Oded; Collins, Michael A; Peskin, Uri

    2010-03-28

    A quantum sampling algorithm for the interpolation of diabatic potential energy matrices by the Grow method is introduced. The new procedure benefits from penetration of the wave packet into classically forbidden regions, and the accurate quantum mechanical description of nonadiabatic transitions. The increased complexity associated with running quantum dynamics is reduced by using approximate low order expansions of the nuclear wave function within a Multi-configuration time-dependent Hartree scheme during the Grow process. The sampling algorithm is formulated and applied for three representative test cases, demonstrating the recovery of analytic potentials by the interpolated ones, and the convergence of a dynamic observable.

  2. The Quantum Energy Saver design and Fuel-saving application

    Science.gov (United States)

    Fang, Xiong; Mao, Wenwu; Shen, Xisheng; LI, Jianyu; Huang, Wenchao; Chen, Zhixin

    2016-11-01

    In order to reduce the high fuel consumption of the shipping industry, a new type of quantum energy saver device is studied and developed. According to a period of time to use the energy saving device and the users’ feedback, by recording the fuel consumption of diesel engine usage, and comparing the changes in fuel consumption before and after the installation of quantum economizer in the same ship, it can reflected the ability of the fuel consumption. After analyzing the data, it shows that the installation of quantum economizer can significantly reduce the fuel consumption of a diesel engine ship. The analysis and application of this paper can play an important role in saving energy and reducing consumption, and provide a reference for other related research.

  3. Addressing student models of energy loss in quantum tunnelling

    CERN Document Server

    Wittmann, M C; Bao, L; Wittmann, Micael C.; Morgan, Jeffrey T.; Bao, Lei

    2005-01-01

    We report on a multi-year, multi-institution study to investigate student reasoning about energy in the context of quantum tunnelling. We use ungraded surveys, graded examination questions, individual clinical interviews, and multiple-choice exams to build a picture of the types of responses that students typically give. We find that two descriptions of tunnelling through a square barrier are particularly common. Students often state that tunnelling particles lose energy while tunnelling. When sketching wave functions, students also show a shift in the axis of oscillation, as if the height of the axis of oscillation indicated the energy of the particle. We find inconsistencies between students' conceptual, mathematical, and graphical models of quantum tunnelling. As part of a curriculum in quantum physics, we have developed instructional materials to help students develop a more robust and less inconsistent picture of tunnelling, and present data suggesting that we have succeeded in doing so.

  4. Communication via an entangled coherent quantum network

    Energy Technology Data Exchange (ETDEWEB)

    El Allati, A; Hassouni, Y [Faculte des Sciences, Departement de Physique, Laboratoire de Physique Theorique URAC 13, Universite Mohammed V Agdal Rabat, Avenue Ibn Battouta, B.P. 1014, Rabat (Morocco); Metwally, N, E-mail: Nmetwally@gmail.com [Mathematics Department, College of Science, University of Bahrain, PO Box 32038 (Bahrain)

    2011-06-01

    A quantum network (QN) is constructed via maximum entangled coherent states. The possibility of using this network to achieve quantum communication between multi-participants is investigated. We showed that the probability of the successful teleportation of an unknown state depends on the size of the used network. As the number of participants increases, the success probability does not depend on the intensity of the field. Implementing a quantum teleportation protocol via a noisy QN is discussed. The unknown state can be teleported perfectly with small values of the field intensity and larger values of the noise strength. The success probability of this suggested protocol increases abruptly for larger values of the noise strength and gradually for small values. For small-size QNs, the fidelity of the teleported state decreases smoothly, whereas it decreases abruptly for larger-sized networks.

  5. Exact Ultra Cold Neutrons' Energy Spectrum in Gravitational Quantum Mechanics

    CERN Document Server

    Pedram, Pouria

    2013-01-01

    We find exact energy eigenvalues and eigenfunctions of the quantum bouncer in the presence of the minimal length uncertainty and the maximal momentum. This form of Generalized (Gravitational) Uncertainty Principle (GUP) agrees with various theories of quantum gravity and predicts a minimal length uncertainty proportional to $\\hbar\\sqrt{\\beta}$ and a maximal momentum proportional to $1/\\sqrt{\\beta}$, where $\\beta$ is the deformation parameter. We also find the semiclassical energy spectrum and discuss the effects of this GUP on the transition rate of the ultra cold neutrons in gravitational spectrometers. Then, based on the Nesvizhevsky's famous experiment, we obtain an upper bound on the dimensionless GUP parameter.

  6. Exact ultra cold neutrons' energy spectrum in gravitational quantum mechanics

    Science.gov (United States)

    Pedram, Pouria

    2013-10-01

    We find exact energy eigenvalues and eigenfunctions of the quantum bouncer in the presence of the minimal length uncertainty and the maximal momentum. This form of Generalized (Gravitational) Uncertainty Principle (GUP) agrees with various theories of quantum gravity and predicts a minimal length uncertainty proportional to and a maximal momentum proportional to , where β is the deformation parameter. We also find the semiclassical energy spectrum and discuss the effects of this GUP on the transition rate of the ultra cold neutrons in gravitational spectrometers. Then, based on Nesvizhevsky's famous experiment, we obtain an upper bound on the dimensionless GUP parameter.

  7. Binding Energy of Excitons in a Quantum Ring

    Institute of Scientific and Technical Information of China (English)

    XIE Wen-Fang

    2008-01-01

    The binding energy of excitons confined to a quantum ring under the influence of perpendicular homogeneous magnetic field is calculated as a function of the ring radius. Calculations are made by using the method of exact diagonalization within the effective-mass approximation. The feature of binding energy of the ground state as a function of the ring radius for several values of the magnetic field has been revealed. The interesting feature of our study is that, in a quantum ring, the geometric structure of excitons may reveal transition.

  8. Maximum Power Output of Quantum Heat Engine with Energy Bath

    Directory of Open Access Journals (Sweden)

    Shengnan Liu

    2016-05-01

    Full Text Available The difference between quantum isoenergetic process and quantum isothermal process comes from the violation of the law of equipartition of energy in the quantum regime. To reveal an important physical meaning of this fact, here we study a special type of quantum heat engine consisting of three processes: isoenergetic, isothermal and adiabatic processes. Therefore, this engine works between the energy and heat baths. Combining two engines of this kind, it is possible to realize the quantum Carnot engine. Furthermore, considering finite velocity of change of the potential shape, here an infinite square well with moving walls, the power output of the engine is discussed. It is found that the efficiency and power output are both closely dependent on the initial and final states of the quantum isothermal process. The performance of the engine cycle is shown to be optimized by control of the occupation probability of the ground state, which is determined by the temperature and the potential width. The relation between the efficiency and power output is also discussed.

  9. Evaporation of (quantum) black holes and energy conservation

    CERN Document Server

    Torres, R; Lorente-Espin, O

    2013-01-01

    We consider Hawking radiation as due to a tunneling process in a black hole were quantum corrections, derived from Quantum Einstein Gravity, are taken into account. The consequent derivation, satisfying conservation laws, leads to a deviation from an exact thermal spectrum. The non-thermal radiation is shown to carry information out of the black hole. Under the appropriate approximation, a quantum corrected temperature is assigned to the black hole. The evolution of the quantum black hole as it evaporates is then described by taking into account the full implications of energy conservation as well as the back-scattered radiation. It is shown that, as a critical mass of the order of Planck's mass is reached, the evaporation process decelerates abruptly while the black hole mass decays towards this critical mass.

  10. Evaporation of (quantum) black holes and energy conservation

    Energy Technology Data Exchange (ETDEWEB)

    Torres, R., E-mail: ramon.torres-herrera@upc.edu [Department of Applied Physics, UPC, Barcelona (Spain); Fayos, F., E-mail: f.fayos@upc.edu [Department of Applied Physics, UPC, Barcelona (Spain); Lorente-Espín, O., E-mail: oscar.lorente-espin@upc.edu [Department of Physics and Nuclear Engineering, UPC, Barcelona (Spain)

    2013-03-13

    We consider Hawking radiation as due to a tunneling process in a black hole were quantum corrections, derived from Quantum Einstein Gravity, are taken into account. The consequent derivation, satisfying conservation laws, leads to a deviation from an exact thermal spectrum. This has consequences for the information loss paradox since the non-thermal radiation is shown to carry information out of the black hole. Under the appropriate approximation, a quantum corrected temperature is assigned to the black hole. The evolution of the quantum black hole as it evaporates is then described by taking into account the full implications of energy conservation as well as the backscattered radiation. It is shown that, as a critical mass of the order of Planck's mass is reached, the evaporation process decelerates abruptly while the black hole mass decays towards this critical mass.

  11. Emergent dark energy via decoherence in quantum interactions

    CERN Document Server

    Altamirano, Natacha; Khosla, Kiran; Mann, Robert B; Milburn, Gerard

    2016-01-01

    Much effort has been devoted into understanding the quantum mechanical properties of gravitational interactions. Here we explore the recent suggestion that gravitational interactions are a fundamental classical channel that is described by continuous quantum measurements and feedforward (CQMF). Specifically, we investigate the possibility that some properties of our universe, modeled using a Friedman-Robertson-Walker metric, can emerge from CQMF by introducing an underlying quantum system for the dynamical variables, avoiding well known difficulties in trying to quantize the spacetime itself. We show that the quantum decoherence necessary in such a measurement model manifests itself as a dark energy fluid that fills the spacetime and whose equation of state asymptotically oscillates around the value $w=-1/3$, regardless of the spatial curvature, which provides the bound between accelerating and decelerating expanding FRW cosmologies.

  12. Scaling of the Coulomb Energy Due to Quantum Fluctuations in the Charge on a Quantum Dot

    DEFF Research Database (Denmark)

    Molenkamp, L. W; Flensberg, Karsten; Kemerink, M.

    1995-01-01

    The charging energy of a quantum dot is measured through the effect of its potential on the conductance of a second dot. This technique allows a measurement of the scaling of the dot's charging energy with the conductance of the tunnel barriers leading to the dot. We find that the charging energy...... scales quadratically with the reflection probability of the barriers. The observed power law agrees with a recent theory....

  13. Teleportation of an arbitrary two-qudit state based on the non-maximally four-qudit cluster state

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Two different schemes are presented for quantum teleportation of an arbitrary two-qudit state using a non-maximally four-qudit cluster state as the quantum channel. The first scheme is based on the Bell-basis measurements and the re-ceiver may probabilistically reconstruct the original state by performing proper transformation on her particles and an auxiliary two-level particle; the second scheme is based on the generalized Bell-basis measurements and the probability of successfully teleporting the unknown state depends on those measurements which are adjusted by Alice. A comparison of the two schemes shows that the latter has a smaller probability than that of the former and contrary to the former, the channel information and auxiliary qubit are not necessary for the receiver in the latter.

  14. Quantum Gravity at Very High Energies

    CERN Document Server

    Gamboa-Rios, J

    2001-01-01

    The problem of time and the quantization of three dimensional gravity in the strong coupling regime is studied following path integral methods. The time is identified with the volume of spacetime. We show that the effective action describes an infinite set of massless relativistic particles moving in a curved three-dimensional target space, i.e. a tensionless 3-brane on a curved background. If the cosmological constant is zero the target space is flat and there is no ` ` graviton" propagation, i.e. $G[g_{ij} (2), g_{ij} (1)] = 0$). If the cosmological constant is different from zero, 3D gravity is both classical and quantum mechanically soluble. Indeed, we find the following results: i) The general exact solutions of the Einstein equations are singular at $t=0$ showing the existence of a big bang in this regime and ii) the propagation amplitude between two geometries $$ vanishes as $t \\to 0$, suggesting that big-bang is suppressed quantum mechanically. This result is also valid in $D>3$.

  15. TELEPORTATION OF A TWO-PARTICLE ENTANGLED STATE

    Institute of Scientific and Technical Information of China (English)

    叶柳; 姚春梅; 郭光灿

    2001-01-01

    A scheme for teleporting a two-particle entangled state via a three-particle entangled state is proposed. It is shown that the probability of successful teleportation is twice the modulus square of the smaller Schmidt coefficient of the entangled three-particle state.

  16. Teleportation of Unknown Superpositions of Collective Atomic Coherent States

    Institute of Scientific and Technical Information of China (English)

    ZHENG ShiBiao

    2001-01-01

    We propose a scheme to teleport an unknown superposition of two atomic coherent states with different phases. Our scheme is based on resonant and dispersive atom-field interaction. Our scheme provides a possibility of teleporting macroscopic superposition states of many atoms first time.``

  17. Probabilistic Teleportation of an Arbitrary n-Particle Entangled State

    Institute of Scientific and Technical Information of China (English)

    XI Yong-Jun; FANG Jian-Xing; ZHU Shi-Qun; GUO Zhan-Ying

    2005-01-01

    A scheme for teleporting an arbitrary n-particle entangled state via n pairs of non-maximally entangled states is proposed. The probability of successful teleportation is determined only by the smaller coefficients of the partially entangled pairs. The method is very easy to be realized.

  18. Teleportation of Two-Particle Entangled State via Cluster State

    Institute of Scientific and Technical Information of China (English)

    LI Da-Chuang; CAO Zhuo-Liang

    2007-01-01

    In this paper,two schemes for teleporting an unknown two-particle entangled state from the sender (Alice)to the receiver (Bob) via a four-particle entangled cluster state are proposed.In these two schemes,the unknown twoparticle entangled state can be teleported perfectly.The successful probabilities and fidelities of the schemes can reach unity.

  19. Nonlinearly-enhanced energy transport in many dimensional quantum chaos

    KAUST Repository

    Brambila, D. S.

    2013-08-05

    By employing a nonlinear quantum kicked rotor model, we investigate the transport of energy in multidimensional quantum chaos. This problem has profound implications in many fields of science ranging from Anderson localization to time reversal of classical and quantum waves. We begin our analysis with a series of parallel numerical simulations, whose results show an unexpected and anomalous behavior. We tackle the problem by a fully analytical approach characterized by Lie groups and solitons theory, demonstrating the existence of a universal, nonlinearly-enhanced diffusion of the energy in the system, which is entirely sustained by soliton waves. Numerical simulations, performed with different models, show a perfect agreement with universal predictions. A realistic experiment is discussed in two dimensional dipolar Bose-Einstein-Condensates (BEC). Besides the obvious implications at the fundamental level, our results show that solitons can form the building block for the realization of new systems for the enhanced transport of matter.

  20. Electron energy spectrum in core-shell elliptic quantum wire

    Directory of Open Access Journals (Sweden)

    V.Holovatsky

    2007-01-01

    Full Text Available The electron energy spectrum in core-shell elliptic quantum wire and elliptic semiconductor nanotubes are investigated within the effective mass approximation. The solution of Schrodinger equation based on the Mathieu functions is obtained in elliptic coordinates. The dependencies of the electron size quantization spectrum on the size and shape of the core-shell nanowire and nanotube are calculated. It is shown that the ellipticity of a quantum wire leads to break of degeneration of quasiparticle energy spectrum. The dependences of the energy of odd and even electron states on the ratio between semiaxes are of a nonmonotonous character. The anticrosing effects are observed at the dependencies of electron energy spectrum on the transversal size of the core-shell nanowire.

  1. Quantum Chromodynamics and Nuclear Physics at Extreme Energy Density

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, B.; Bass, S.A.; Chandrasekharan, S.; Mehen, T.; Springer, R.P.

    2005-11-07

    The report describes research in theoretical quantum chromodynamics, including effective field theories of hadronic interactions, properties of strongly interacting matter at extreme energy density, phenomenology of relativistic heavy ion collisions, and algorithms and numerical simulations of lattice gauge theory and other many-body systems.

  2. Electron Energy Level Statistics in Graphene Quantum Dots

    NARCIS (Netherlands)

    De Raedt, H.; Katsnellson, M. I.; Katsnelson, M.I.

    2008-01-01

    Motivated by recent experimental observations of size quantization of electron energy levels in graphene quantum dots [7] we investigate the level statistics in the simplest tight-binding model for different dot shapes by computer simulation. The results are in a reasonable agreement with the experi

  3. Causality and universality in low-energy quantum scattering

    Energy Technology Data Exchange (ETDEWEB)

    Hammer, H.-W., E-mail: hammer@hiskp.uni-bonn.d [Helmholtz-Institut fuer Strahlen- und Kernphysik (Theorie) and Bethe Center for Theoretical Physics, Universitaet Bonn, D-53115 Bonn (Germany); Lee, Dean [Department of Physics, North Carolina State University, Raleigh, NC 27695 (United States); Helmholtz-Institut fuer Strahlen- und Kernphysik (Theorie) and Bethe Center for Theoretical Physics, Universitaet Bonn, D-53115 Bonn (Germany)

    2009-11-16

    We generalize Wigner's causality bounds and Bethe's integral formula for the effective range to arbitrary dimension and arbitrary angular momentum. Moreover, we discuss the impact of these constraints on the separation of low- and high-momentum scales and universality in low-energy quantum scattering.

  4. Probabilistic Teleportation of the Three-Particle Entangled State by the Partial Three-Particle Entangled State and the Three-Particle Entangled W State

    Institute of Scientific and Technical Information of China (English)

    戴宏毅; 李承祖; 陈平形

    2003-01-01

    We present a scheme to teleport an unknown three-particle entangled state from a sender to either one of two receivers. The partial three-particle entangled state and the three-particle entangled W state are considered as the quantum channels. An unknown three-particle entangled state can be perfectly teleported probabilistically by performing two generalized Bell measurements and the Hadamard operation at the sender's side and introducing an appropriate unitary transformation in each receiver's laboratory conditioned on the simple measurement outcome of the other. All kinds of unitary transformations are given in details. This scheme can be directly generalized to teleport an unknown three-particle entangled state from a sender to any one of N receivers by the partial three-particle entangled state and the (N + 1)-particle entangled W state.

  5. Quantum information transmission in the quantum wireless multihop network based on Werner state

    Science.gov (United States)

    Shi, Li-Hui; Yu, Xu-Tao; Cai, Xiao-Fei; Gong, Yan-Xiao; Zhang, Zai-Chen

    2015-05-01

    Many previous studies about teleportation are based on pure state. Study of quantum channel as mixed state is more realistic but complicated as pure states degenerate into mixed states by interaction with environment, and the Werner state plays an important role in the study of the mixed state. In this paper, the quantum wireless multihop network is proposed and the information is transmitted hop by hop through teleportation. We deduce a specific expression of the recovered state not only after one-hop teleportation but also across multiple intermediate nodes based on Werner state in a quantum wireless multihop network. We also obtain the fidelity of multihop teleportation. Project supported by the Prospective Future Network Project of Jiangsu Province, China (Grant No. BY2013095-1-18) and the Independent Project of State Key Laboratory of Millimeter Waves (Grant No. Z201504).

  6. Quantum Model of Energy Transport in Collagen Molecules

    Institute of Scientific and Technical Information of China (English)

    XIAO Yi; LIN Xian-Zhe

    2001-01-01

    A semi-quantum model for energy transport in collagen molecules is presented. Soliton-like dynamics of this model is investigated numerically without and with the temperature effect taking into account. It is found that in both the cases energy can transport for a long distance along the collagen chain. This indicates that collagen molecules can be taken as a candidate for the acupuncture channel.

  7. Quantum Inequality for Negative Energy Density States of Massive Dirac Field in Four-Dimensional Spacetime

    Institute of Scientific and Technical Information of China (English)

    舒维星; 吴普训; 余洪伟

    2003-01-01

    Negative energy density and the quantum inequality are examined for the Dirac field. A proof is given of the quantum inequality for negative energy densities in the massive Dirac field produced by the superposition of two single particle electron states.

  8. Emission energy control of semiconductor quantum dots using phase change material

    Science.gov (United States)

    Kanazawa, Shohei; Sato, Yu; Yamamura, Ariyoshi; Saiki, Toshiharu

    2015-03-01

    Semiconductor quantum dots have paid much attention as it is a promising candidate for quantum, optical devices, such as quantum computer and quantum dot laser. We propose a local emission energy control method of semiconductor quantum dots using applying strain by volume expansion of phase change material. Phase change material can change its phase crystalline to amorphous, and the volume expand by its phase change. This method can control energy shift direction and amount by amorphous religion and depth. Using this method, we matched emission energy of two InAs/InP quantum dots. This achievement can connect to observing superradiance phenomenon and quantum dot coupling effect.

  9. Probabilistically Controlled Teleportation of an Arbitrary Two-Qubit State via Positive Operator-Valued Measure

    Institute of Scientific and Technical Information of China (English)

    XU Hai-Feng; HAN Lian-Fang

    2013-01-01

    We propose a tripartite scheme for probabilistically teleporting an arbitrary two-qubit state with a fourqubit duster-class state and a Bell-class state as the quantum channels.In the scheme,the sender and the controller make Bell-state measurements (BSMs) on their respective qubit pairs.With their measurement results,the receiver can reconstruct the original state probabilistically by introducing two auxiliary particles and making appropriate unitary operations and positive operator-valued measure (POVM) instead of usual projective measurement.Moreover,the total success probability and classical communication cost of the present protocol are also worked out.

  10. Averaged null energy condition and quantum inequalities in curved spacetime

    CERN Document Server

    Kontou, Eleni-Alexandra

    2015-01-01

    The Averaged Null Energy Condition (ANEC) states that the integral along a complete null geodesic of the projection of the stress-energy tensor onto the tangent vector to the geodesic cannot be negative. ANEC can be used to rule out spacetimes with exotic phenomena, such as closed timelike curves, superluminal travel and wormholes. We prove that ANEC is obeyed by a minimally-coupled, free quantum scalar field on any achronal null geodesic (not two points can be connected with a timelike curve) surrounded by a tubular neighborhood whose curvature is produced by a classical source. To prove ANEC we use a null-projected quantum inequality, which provides constraints on how negative the weighted average of the renormalized stress-energy tensor of a quantum field can be. Starting with a general result of Fewster and Smith, we first derive a timelike projected quantum inequality for a minimally-coupled scalar field on flat spacetime with a background potential. Using that result we proceed to find the bound of a qu...

  11. The quantum Kirchhoff equation and quantum current and energy spectrum of a homogeneous mesoscopic dissipation transmission line

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    On the basis of quantization of charge, the loop equations of quantum circuits are investigated by using the Heisenberg motion equation for a mesoscopic dissipation transmission line. On the supposition that the system has a symmetry under translation in charge space, the quantum current and the quantum energy spectrum in the mesoscopic transmission line are given by solving their eigenvalue equations. Results show that the quantum current and the quantum energy spectrum are not only related to the parameters of the transmission line, but also dependent on the quantized character of the charge obviously.

  12. Low Energy Description of Quantum Gravity and Complementarity

    CERN Document Server

    Nomura, Yasunori; Weinberg, Sean J

    2013-01-01

    We propose an explicit framework in which low energy dynamics of quantum gravity is described preserving locality, and yet taking into account the effects that are not captured by the naive global spacetime picture, e.g. those associated with black hole complementarity. Our framework employs a "special relativistic" description of gravity; specifically, gravity is treated as a force measured by the observer tied to the coordinate system associated with a freely falling local Lorentz frame. We explicitly identify regions of spacetime in which low energy local descriptions are applicable as viewed from the freely falling frame; in particular, we identify a surface called the gravitational observer horizon on which the local proper acceleration measured in the observer's coordinates becomes the cutoff (string) scale. This allows for separating clearly between the "low-energy" local physics and "trans-Planckian" intrinsically quantum gravitational (stringy) physics, and allows for developing clear physical pictur...

  13. Geometrical effects on energy transfer in disordered open quantum systems

    CERN Document Server

    Mohseni, M; Lloyd, S; Omar, Y; Rabitz, H

    2013-01-01

    We explore various design principles for efficient excitation energy transport in complex quantum systems. We investigate energy transfer efficiency in randomly disordered geometries consisting of up to 20 chromophores to explore spatial and spectral properties of small natural/artificial Light-Harvesting Complexes (LHC). We find significant statistical correlations among highly efficient random structures with respect to ground state properties, excitonic energy gaps, multichromophoric spatial connectivity, and path strengths. These correlations can even exist beyond the optimal regime of environment-assisted quantum transport. For random configurations embedded in spatial dimensions of 30 A and 50 A, we observe that the transport efficiency saturates to its maximum value if the systems contain 7 and 14 chromophores respectively. Remarkably, these optimum values coincide with the number of chlorophylls in (Fenna-Matthews-Olson) FMO protein complex and LHC II monomers, respectively, suggesting a potential nat...

  14. Quantum Haplodynamics, Dark Matter, and Dark Energy

    Directory of Open Access Journals (Sweden)

    Harald Fritzsch

    2014-01-01

    of the associated gauge group SU(2h is of the order of Λh≃0.3 TeV. One scalar state has zero haplon number and is the resonance observed at the LHC. In addition, there exist new bound states of haplons with no counterpart in the SM, having a mass of the order of 0.5 TeV up to a few TeV. In particular, a neutral scalar state with haplon number 4 is stable and can provide the dark matter in the universe. The QHD, QCD, and QED couplings can unify at the Planck scale. If this scale changes slowly with cosmic time, all of the fundamental couplings, the masses of the nucleons and of the DM particles, including the cosmological term (or vacuum energy density, will evolve with time. This could explain the dark energy of the universe.

  15. Conversion of the zero-point energy of the quantum vacuum into classical mechanical energy

    Energy Technology Data Exchange (ETDEWEB)

    Turtur, Claus Wilhelm

    2010-07-01

    A perpetual motion machine - this can never exist. But energy sources nearly disregarded up to now - they exist. These are energy sources, which have been hardly under investigation, so that mankind did not yet learn how to get benefit from them. Most part of the universe consists of such energy, which is still called 'invisible'. A part of this energy is to be found within the so called zero-point oscillations of the quantum vacuum, thus within the empty void from the perspective of quantum physics. The author of the book is physicist. He theoretically developed and then experimentally verified a method for the conversion of vacuum energy into classical mechanical energy. His technique is one of the very few approaches known up to know. The most prominent approaches to convert vacuum energy are described in this book in many scientific details, and they are compared with other known proposals for the use of vacuum energy. (orig.)

  16. Binding energy of donors in symmetric triangular quantum wells

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ji-ye; LIANG Xi-xia

    2005-01-01

    Hydrogen-like donor impurity states in symmetric triangular quantum wells are investigated by using a variational method.Both the effects of the variable effective mass of electrons and the spatially dependent dielectric constant are considered in the calculation.The numerical results show that the binding energy depends on not only the effective mass and dielectric constant but also the spatial distribution of electron probability density.The binding energies of donor states get the maximums at the well-center.The results are also compared with those obtained in parabolic and square wells.It is seen that the triangular well support the highest binding energies for donor states.

  17. Clusters, Quantum Confinement and Energy Storage

    Science.gov (United States)

    Connerade, Jean-Patrick

    One of the challenges posed by the demand for clean urban transportation is the compact and cyclically recoverable storage of energy in quantities sufficient for propulsion. Promising routes, such as the reversible insertion of Li+ ions inside solids for `rocking chair' batteries, require a deformable host material with no irreversibility. Such `soft' deformations are in general highly complex, but the compressibility of atoms or larger systems can be studied directly in situations with simpler symmetry. Thus, the search for `soft' materials leads one to consider certain types of cluster, as well as linear or nearly-spherical structures (chains of metallofullerenes, for example) whose deformations can be computed from the Schrodinger equation. Extended or `giant' atomic models allow one to construct compression-dilation cycles analogous in a rough sense to the Carnot cycle of classical thermodynamics. This simplified approach suggests that, even for idealised systems, there are constraints on the reversible storage and recovery of energy, and that (when applied to realistic structures) modelling based on such principles might help in the selection of appropriate materials.

  18. Exponential vanishing of the ground-state gap of the quantum random energy model via adiabatic quantum computing

    Energy Technology Data Exchange (ETDEWEB)

    Adame, J.; Warzel, S., E-mail: warzel@ma.tum.de [Zentrum Mathematik, TU München, Boltzmannstr. 3, 85747 Garching (Germany)

    2015-11-15

    In this note, we use ideas of Farhi et al. [Int. J. Quantum. Inf. 6, 503 (2008) and Quantum Inf. Comput. 11, 840 (2011)] who link a lower bound on the run time of their quantum adiabatic search algorithm to an upper bound on the energy gap above the ground-state of the generators of this algorithm. We apply these ideas to the quantum random energy model (QREM). Our main result is a simple proof of the conjectured exponential vanishing of the energy gap of the QREM.

  19. Coherent communication with continuous quantum variables

    Science.gov (United States)

    Wilde, Mark M.; Krovi, Hari; Brun, Todd A.

    2007-06-01

    The coherent bit (cobit) channel is a resource intermediate between classical and quantum communication. It produces coherent versions of teleportation and superdense coding. We extend the cobit channel to continuous variables by providing a definition of the coherent nat (conat) channel. We construct several coherent protocols that use both a position-quadrature and a momentum-quadrature conat channel with finite squeezing. Finally, we show that the quality of squeezing diminishes through successive compositions of coherent teleportation and superdense coding.

  20. Scheme for teleportation of unknown states of trapped ion

    Institute of Scientific and Technical Information of China (English)

    Chen Mei-Feng; Ma Song-She

    2008-01-01

    A scheme is presented for teleporting an unknown state in a trapped ion system.The scheme only requires a single laser beam.It allows the trap to be in any state with a few phonons,e.g.a thermal motion.Furthermore,it works in the regime,where the Rabi frequency of the laser is on the order of the trap frequency.Thus,the teleportation speed is greatly increased,which is important for decreasing the decoherence effect.This idea can also be used to teleport an unknown ionic entangled state.

  1. Finite Casimir Energies in Renormalizable Quantum Field Theory

    CERN Document Server

    Milton, K A

    2004-01-01

    Quantum vacuum energy has been known to have observable consequences since 1948 when Casimir calculated the force of attraction between parallel uncharged plates, a phenomenon confirmed experimentally with ever increasing precision. Casimir himself suggested that a similar attractive self-stress existed for a conducting spherical shell, but Boyer obtained a repulsive stress. Other geometries and higher dimensions have been considered over the years. Local effects, and divergences associated with surfaces and edges have been investigated by several authors. Quite recently, Graham et al. have re-examined such calculations, using conventional techniques of perturbative quantum field theory to remove divergences, and have suggested that previous self-stress results may be suspect. Here we show that most of the examples considered in their work are misleading; in particular, it is well-known that in two dimensions a circular boundary has a divergence in the Casimir energy for massless fields, while for general dim...

  2. Calculating Casimir Energies in Renormalizable Quantum Field Theory

    CERN Document Server

    Milton, K A

    2003-01-01

    Quantum vacuum energy has been known to have observable consequences since 1948 when Casimir calculated the force of attraction between parallel uncharged plates, a phenomenon confirmed experimentally with ever increasing precision. Casimir himself suggested that a similar attractive self-stress existed for a conducting spherical shell, but Boyer obtained a repulsive stress. Other geometries and higher dimensions have been considered over the years. Local effects, and divergences associated with surfaces and edges have been considered by several authors. Quite recently, Graham et al. have re-examined such calculations, using conventional techniques of perturbative quantum field theory to remove divergences, and have suggested that previous self-stress results may be suspect. Here we show that the examples considered in their work are misleading; in particular, it is well-known that in two dimensions a circular boundary has a divergence in the Casimir energy for massless fields, while for general dimension $D$...

  3. Natural Regulation of Energy Flow in a Green Quantum Photocell

    CERN Document Server

    Arp, Trevor B; Aji, Vivek; Gabor, Nathaniel M

    2015-01-01

    Manipulating the flow of energy in nanoscale and molecular photonic devices is of both fundamental interest and central importance for applications in light harvesting optoelectronics. Under erratic solar irradiance conditions, unregulated power fluctuations in a light harvesting photocell lead to inefficient energy storage in conventional solar cells and potentially fatal oxidative damage in photosynthesis. Here, we show that regulation against these fluctuations arises naturally within a two-channel quantum heat engine photocell, thus enabling the efficient conversion of varying incident solar spectrum at Earth's surface. Remarkably, absorption in the green portion of the spectrum is avoided, as it provides no inherent regulatory benefit. Our findings illuminate a quantum structural origin of regulation, provide a novel optoelectronic design strategy, and may elucidate the link between photoprotection in photosynthesis and the predominance of green plants on Earth.

  4. Exciton and Biexciton Binding Energies in Rectangular Quantum Dots

    Institute of Scientific and Technical Information of China (English)

    LIU Yong-Hui; KONG Xiao-Jun

    2005-01-01

    @@ In the effective mass approximation, using the variational technology and a method of expanding the wavefunctions of exciton in terms of the eigenfunctions of the noninteracting electron-hole system, we calculate the exciton and biexciton ground state binding energies for rectangular quantum dots (QDs). In the calculation, a three-dimensional Fourier expansion of Coulomb potential is used to remove the numerical difficulty with the 1/r singularity, and it considerably reduces the computational effort. Our results agree fairly well with the previous results. It is found that the binding energies are highly correlated to the size of QDs. The quantum confinement effect of spherical QDs about biexciton is obviously larger than that of rectangular QDs when the well width is narrower than 2.0aB.

  5. Computation of energy states of hydrogenic quantum dot with two-electrons

    Science.gov (United States)

    Yakar, Y.; Özmen, A.; ćakır, B.

    2016-03-01

    In this study we have investigated the electronic structure of the hydrogenic quantum dot with two electrons inside an impenetrable potential surface. The energy eigenvalues and wavefunctions of the ground and excited states of spherical quantum dot have been calculated by using the Quantum Genetic Algorithm (QGA) and Hartree-Fock Roothaan (HFR) method, and the energies are investigated as a function of dot radius. The results show that as dot radius increases, the energy of quantum dot decreases.

  6. Quantum Information Theory - an Invitation

    OpenAIRE

    Werner, R. F.

    2001-01-01

    We give a non-technical introduction of the basic concepts of Quantum Information Theory along the distinction between possible and impossible machines. We then proceed to describe the mathematical framework of Quantum Information Theory. The capacities of a quantum channel for classical and for quantum information are defined in a unified scheme, and a mathematical characterization of all teleportation and dense coding schemes is given.

  7. Quantum information causality.

    Science.gov (United States)

    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.

  8. Backward Evolving Quantum States

    CERN Document Server

    Vaidman, L

    2006-01-01

    The basic concept of the two-state vector formalism, which is the time symmetric approach to quantum mechanics, is the backward evolving quantum state. However, due to the time asymmetry of the memory's arrow of time, the possible ways to manipulate a backward evolving quantum state differ from those for a standard, forward evolving quantum state. The similarities and the differences between forward and backward evolving quantum states regarding the no-cloning theorem, nonlocal measurements, and teleportation are discussed. The results are relevant not only in the framework of the two-state vector formalism, but also in the framework of retrodictive quantum theory.

  9. Towards a quantum internet

    Science.gov (United States)

    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.

  10. Carrier density dependence of plasmon-enhanced nonradiative energy transfer in a hybrid quantum well-quantum dot structure.

    Science.gov (United States)

    Higgins, L J; Karanikolas, V D; Marocico, C A; Bell, A P; Sadler, T C; Parbrook, P J; Bradley, A L

    2015-01-26

    An array of Ag nanoboxes fabricated by helium-ion lithography is used to demonstrate plasmon-enhanced nonradiative energy transfer in a hybrid quantum well-quantum dot structure. The nonradiative energy transfer, from an InGaN/GaN quantum well to CdSe/ZnS nanocrystal quantum dots embedded in an ~80 nm layer of PMMA, is investigated over a range of carrier densities within the quantum well. The plasmon-enhanced energy transfer efficiency is found to be independent of the carrier density, with an efficiency of 25% reported. The dependence on carrier density is observed to be the same as for conventional nonradiative energy transfer. The plasmon-coupled energy transfer enhances the QD emission by 58%. However, due to photoluminescence quenching effects an overall increase in the QD emission of 16% is observed.

  11. D{sup -} energy spectrum in toroidal quantum ring

    Energy Technology Data Exchange (ETDEWEB)

    Gomez, C A; Gutierrez, W; Garcia, L F [Universidad Industrial de Santander, Bucaramanga (Colombia); Marin, J H, E-mail: jhmarin@unal.edu.c [Universidad Nacional-Colombia, Medellin-Colombia, AA3840 (Colombia)

    2009-05-01

    The structure of energy spectrum of the negative donor centre in a toroidal-shaped quantum ring with two different morphologies of the cross-section is analyzed. By using the adiabatic procedure we have deduced a one-dimensional wave equation with periodic conditions which describes the low-lying energy levels related to the electrons rotation around the symmetry axis. Our results are in good agreement with those previously obtained as the size of the ring cross-section tends to zero.

  12. The energy-level crossing behavior and quantum Fisher information in a quantum well with spin-orbit coupling.

    Science.gov (United States)

    Wang, Z H; Zheng, Q; Wang, Xiaoguang; Li, Yong

    2016-03-02

    We study the energy-level crossing behavior in a two-dimensional quantum well with the Rashba and Dresselhaus spin-orbit couplings (SOCs). By mapping the SOC Hamiltonian onto an anisotropic Rabi model, we obtain the approximate ground state and its quantum Fisher information (QFI) via performing a unitary transformation. We find that the energy-level crossing can occur in the quantum well system within the available parameters rather than in cavity and circuit quantum eletrodynamics systems. Furthermore, the influence of two kinds of SOCs on the QFI is investigated and an intuitive explanation from the viewpoint of the stationary perturbation theory is given.

  13. Significance of Negative Energy States in Quantum Field Theory $(1) $

    CERN Document Server

    Chen Sow Hsin

    2002-01-01

    We suppose that there are both particles with negative energies described by $\\QTR{cal}{L}_{W}$ and particles with positive energies described by $\\QTR{cal}{L}_{F},$ $\\QTR{cal}{L=L}_{F\\text{}}+\\QTR{cal}{L}_{W},$ $\\QTR{cal}{L}_{F\\text{}}$ is equivalent to Lagragian density of the conventional QED, $\\QTR{cal}{L}_{W}$ and $\\QTR{cal}{L}_{F\\text{}}$ are symmetric, independent of each other before quantization and dependent on each other after quantization. From this we define transfomation operators and quantize free fields by the transformation operators replacing the creation and annihilation operators in the conventional QED. That the energy of the vacuum state is equal to zero is naturally obtained. Thus we can easily determine the cosmological constant according to data of astronomical observation, and it is possible to correct nonperturbational methods which depend on the energy of the ground state in quantum field theory.

  14. Pseudospectral Gaussian quantum dynamics: Efficient sampling of potential energy surfaces

    Science.gov (United States)

    Heaps, Charles W.; Mazziotti, David A.

    2016-04-01

    Trajectory-based Gaussian basis sets have been tremendously successful in describing high-dimensional quantum molecular dynamics. In this paper, we introduce a pseudospectral Gaussian-based method that achieves accurate quantum dynamics using efficient, real-space sampling of the time-dependent basis set. As in other Gaussian basis methods, we begin with a basis set expansion using time-dependent Gaussian basis functions guided by classical mechanics. Unlike other Gaussian methods but characteristic of the pseudospectral and collocation methods, the basis set is tested with N Dirac delta functions, where N is the number of basis functions, rather than using the basis function as test functions. As a result, the integration for matrix elements is reduced to function evaluation. Pseudospectral Gaussian dynamics only requires O ( N ) potential energy calculations, in contrast to O ( N 2 ) evaluations in a variational calculation. The classical trajectories allow small basis sets to sample high-dimensional potentials. Applications are made to diatomic oscillations in a Morse potential and a generalized version of the Henon-Heiles potential in two, four, and six dimensions. Comparisons are drawn to full analytical evaluation of potential energy integrals (variational) and the bra-ket averaged Taylor (BAT) expansion, an O ( N ) approximation used in Gaussian-based dynamics. In all cases, the pseudospectral Gaussian method is competitive with full variational calculations that require a global, analytical, and integrable potential energy surface. Additionally, the BAT breaks down when quantum mechanical coherence is particularly strong (i.e., barrier reflection in the Morse oscillator). The ability to obtain variational accuracy using only the potential energy at discrete points makes the pseudospectral Gaussian method a promising avenue for on-the-fly dynamics, where electronic structure calculations become computationally significant.

  15. Fluorescence energy transfer in quantum dot/azo dye complexes in polymer track membranes

    Science.gov (United States)

    Gromova, Yulia A.; Orlova, Anna O.; Maslov, Vladimir G.; Fedorov, Anatoly V.; Baranov, Alexander V.

    2013-10-01

    Fluorescence resonance energy transfer in complexes of semiconductor CdSe/ZnS quantum dots with molecules of heterocyclic azo dyes, 1-(2-pyridylazo)-2-naphthol and 4-(2-pyridylazo) resorcinol, formed at high quantum dot concentration in the polymer pore track membranes were studied by steady-state and transient PL spectroscopy. The effect of interaction between the complexes and free quantum dots on the efficiency of the fluorescence energy transfer and quantum dot luminescence quenching was found and discussed.

  16. Dynamics and quantumness of excitation energy transfer through a complex quantum network

    CERN Document Server

    Qin, M; Zhao, X L; Yi, X X

    2015-01-01

    Understanding the mechanisms of efficient and robust energy transfer in organic systems provides us with new insights for the optimal design of artificial systems. In this paper, we explore the dynamics of excitation energy transfer (EET) through a complex quantum network by a toy model consisting of three sites coupled to environments. We study how the coherent evolution and the noise-induced decoherence work together to reach efficient EET and illustrate the role of the phase factor attached to the coupling constant in the EET. By comparing the differences between the Markovian and non-Markovian dynamics, we discuss the effect of environment and the spatial structure of system on the dynamics and the efficiency of EET. A intuitive picture is given to show how the exciton is transferred through the system. Employing the simple model, we show the robustness of EET efficiency under the influence of the environment and elucidate the important role of quantum coherence in EET. We go further to study the quantum ...

  17. Routing protocol for wireless quantum multi-hop mesh backbone network based on partially entangled GHZ state

    Science.gov (United States)

    Xiong, Pei-Ying; Yu, Xu-Tao; Zhang, Zai-Chen; Zhan, Hai-Tao; Hua, Jing-Yu

    2017-08-01

    Quantum multi-hop teleportation is important in the field of quantum communication. In this study, we propose a quantum multi-hop communication model and a quantum routing protocol with multihop teleportation for wireless mesh backbone networks. Based on an analysis of quantum multi-hop protocols, a partially entangled Greenberger-Horne-Zeilinger (GHZ) state is selected as the quantum channel for the proposed protocol. Both quantum and classical wireless channels exist between two neighboring nodes along the route. With the proposed routing protocol, quantum information can be transmitted hop by hop from the source node to the destination node. Based on multi-hop teleportation based on the partially entangled GHZ state, a quantum route established with the minimum number of hops. The difference between our routing protocol and the classical one is that in the former, the processes used to find a quantum route and establish quantum channel entanglement occur simultaneously. The Bell state measurement results of each hop are piggybacked to quantum route finding information. This method reduces the total number of packets and the magnitude of air interface delay. The deduction of the establishment of a quantum channel between source and destination is also presented here. The final success probability of quantum multi-hop teleportation in wireless mesh backbone networks was simulated and analyzed. Our research shows that quantum multi-hop teleportation in wireless mesh backbone networks through a partially entangled GHZ state is feasible.

  18. Anomalous vacuum energy and stability of a quantum liquid

    CERN Document Server

    Trachenko, K

    2016-01-01

    We show that the vacuum (zero-point) energy of a low-temperature quantum liquid is a variable property which changes with the state of the system, in notable contrast to the static vacuum energy in solids commonly considered. We further show that this energy is inherently anomalous: it decreases with temperature and gives negative contribution to system's heat capacity. This effect operates in an equilibrium and macroscopic system, in marked contrast to small or out-of-equilibrium configurations discussed previously. We find that the negative contribution is over-compensated by the positive term from the excitation of longitudinal fluctuations and demonstrate how the overall positive heat capacity is related to the stability of a condensed phase at the microscopic level.

  19. Exciton and donor binding energies in quantum-well wires and quantum dots a fractional-dimensional space approach

    Institute of Scientific and Technical Information of China (English)

    Li Hong; Kong Xiao-Jun

    2004-01-01

    A simple method for calculating the free-exciton binding energies in the fractional-dimensional-space model for single-quantum-well structure has been extended to quantum-well wires and quantum dots, in which the real anisotropic system is modelled through an effective isotropic environment with a fractional dimension. In this scheme, the fractionaldimensional parameter is chosen via an analytical procedure and involves no ansatz. We calculated the ground-state binding energies of excitons and donors in quantum-well wires with rectangular cross sections. Our results are found to be in good agreement with previous variational calculations and available experimental measurements. We also discussed the ground-state exciton binding energy changing with different shapes of quantum-well wires.

  20. Efficient simultaneous dense coding and teleportation with two-photon four-qubit cluster states

    Science.gov (United States)

    Zhang, Cai; Situ, Haozhen; Li, Qin; He, Guang Ping

    2016-08-01

    We firstly propose a simultaneous dense coding protocol with two-photon four-qubit cluster states in which two receivers can simultaneously get their respective classical information sent by a sender. Because each photon has two degrees of freedom, the protocol will achieve a high transmittance. The security of the simultaneous dense coding protocol has also been analyzed. Secondly, we investigate how to simultaneously teleport two different quantum states with polarization and path degree of freedom using cluster states to two receivers, respectively, and discuss its security. The preparation and transmission of two-photon four-qubit cluster states is less difficult than that of four-photon entangled states, and it has been experimentally generated with nearly perfect fidelity and high generation rate. Thus, our protocols are feasible with current quantum techniques.

  1. Diffraction of quantum dots reveals nanoscale ultrafast energy localization.

    Science.gov (United States)

    Vanacore, Giovanni M; Hu, Jianbo; Liang, Wenxi; Bietti, Sergio; Sanguinetti, Stefano; Zewail, Ahmed H

    2014-11-12

    Unlike in bulk materials, energy transport in low-dimensional and nanoscale systems may be governed by a coherent "ballistic" behavior of lattice vibrations, the phonons. If dominant, such behavior would determine the mechanism for transport and relaxation in various energy-conversion applications. In order to study this coherent limit, both the spatial and temporal resolutions must be sufficient for the length-time scales involved. Here, we report observation of the lattice dynamics in nanoscale quantum dots of gallium arsenide using ultrafast electron diffraction. By varying the dot size from h = 11 to 46 nm, the length scale effect was examined, together with the temporal change. When the dot size is smaller than the inelastic phonon mean-free path, the energy remains localized in high-energy acoustic modes that travel coherently within the dot. As the dot size increases, an energy dissipation toward low-energy phonons takes place, and the transport becomes diffusive. Because ultrafast diffraction provides the atomic-scale resolution and a sufficiently high time resolution, other nanostructured materials can be studied similarly to elucidate the nature of dynamical energy localization.

  2. Quantum algorithm for universal implementation of the projective measurement of energy.

    Science.gov (United States)

    Nakayama, Shojun; Soeda, Akihito; Murao, Mio

    2015-05-15

    A projective measurement of energy (PME) on a quantum system is a quantum measurement determined by the Hamiltonian of the system. PME protocols exist when the Hamiltonian is given in advance. Unknown Hamiltonians can be identified by quantum tomography, but the time cost to achieve a given accuracy increases exponentially with the size of the quantum system. In this Letter, we improve the time cost by adapting quantum phase estimation, an algorithm designed for computational problems, to measurements on physical systems. We present a PME protocol without quantum tomography for Hamiltonians whose dimension and energy scale are given but which are otherwise unknown. Our protocol implements a PME to arbitrary accuracy without any dimension dependence on its time cost. We also show that another computational quantum algorithm may be used for efficient estimation of the energy scale. These algorithms show that computational quantum algorithms, with suitable modifications, have applications beyond their original context.

  3. An Emphasis of Electron Energy Calculation in Quantum Wells

    Institute of Scientific and Technical Information of China (English)

    GAOShao-Wen; CAOJun-Cheng; FENGSong-Lin

    2004-01-01

    We investigate various methods for the calculation of the electron energy in semiconductor quantum wells and focus on a matrix algorithm method. The results show better fitness of the factor -h2/2 э/эz 1/m*(z) э/эz than that of -h2/2 1/m*(z) э2/эz2 in the first part of the Schroedinger equation. The effect of nonparabolicity in the conduction band is also discussed.

  4. Potential Energy Surfaces and Quantum Yields for Photochromic Diarylethene Reactions

    Directory of Open Access Journals (Sweden)

    Makoto Hatakeyama

    2013-05-01

    Full Text Available Photochromic diarylethenes (DAEs are among the most promising molecular switching systems for future molecular electronics. Numerous derivatives have been synthesized recently, and experimental quantum yields (QYs have been reported for two categories of them. Although the QY is one of the most important properties in various applications, it is also the most difficult property to predict before a molecule is actually synthesized. We have previously reported preliminary theoretical studies on what determines the QYs in both categories of DAE derivatives. Here, reflecting theoretical analyses of potential energy surfaces and recent experimental results, a rational explanation of the general guiding principle for QY design is presented for future molecular design.

  5. Real single ion solvation free energies with quantum mechanical simulation

    Energy Technology Data Exchange (ETDEWEB)

    Duignan, Timothy TS; Baer, Marcel D.; Schenter, Gregory K.; Mundy, Christopher J.

    2017-09-01

    Single ion solvation free energies are one of the most important properties of electrolyte solution and yet there is ongoing debate about what these values are. Experimental methods can only determine the values for neutral ion pairs. Here, we use DFT interaction potentials with molecular dynamics simulation (DFT-MD) combined with a modified version of the quasi chemical theory (QCT) to calculate these energies for the lithium and fluoride ions. A new method to rigorously correct for the error in the DFT functional is developed and very good agreement with the experimental value for the lithium fluoride pair is obtained. Moreover, this method partitions the energies into physically intuitive terms such as surface potential, cavity and charging energies which are amenable to descriptions with reduced models. Our research suggests that lithium’s solvation energy is dominated by the free energetics of a charged hard sphere, whereas fluoride exhibits significant quantum mechanical behavior that cannot be simply described with a reduced model. We would like to thank Thomas Beck, Shawn Kathmann and Sotiris Xantheas for helpful discussions. Computing resources were generously allocated by PNNLs Institutional Computing program. This research also used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. TTD, GKS and CJM were supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. MDB was supported by MS3 (Materials Synthesis and Simulation Across Scales) Initiative, a Laboratory Directed Research and Development Program at Pacific Northwest National Laboratory (PNNL). PNNL is a multi-program national laboratory operated by Battelle for the U.S. Department of Energy.

  6. Mass renormalization and binding energies in quantum field theory

    Science.gov (United States)

    Lv, Q. Z.; Stefanovich, E.; Su, Q.; Grobe, R.

    2017-10-01

    We compare the predictions of two methods of determining the amount of binding energy between two distinguishable fermions that interact with each other through force-intermediating bosons. Both measures try to quantify this binding energy by the downward shift of the fully interacting two-fermion ground state energy relative to the sum of the corresponding two single-particle ground state energies. The first method computes this energy difference directly from the standard quantum field theoretical Hamiltonian. The second method uses the mass renormalized form of this Hamiltonian. In order to have a concrete example for this comparison, we employ a simple Yukawa-like model system in one spatial dimension. We find that both approaches lead to identical predictions in the second and fourth order perturbation of the coupling constant, and they remain remarkably close even in the strong coupling domain where perturbation theory diverges. This illustrates that there are field theoretical systems for which rather accurate binding energies can be obtained even without the mass renormalization procedure.

  7. Experimental entanglement distillation of mesoscopic quantum states

    DEFF Research Database (Denmark)

    Dong, Ruifang; Lassen, Mikael Østergaard; Heersink, Joel

    2008-01-01

    The distribution of entangled states between distant parties in an optical network is crucial for the successful implementation of various quantum communication protocols such as quantum cryptography, teleportation and dense coding(1-3). However, owing to the unavoidable loss in any real optical...

  8. A Quantum Phase Transition in the Cosmic Ray Energy Distribution

    CERN Document Server

    Widom, A; Srivastava, Y

    2015-01-01

    We here argue that the "knee" of the cosmic ray energy distribution at $E_c \\sim 1$ PeV represents a second order phase transition of cosmic proportions. The discontinuity of the heat capacity per cosmic ray particle is given by $\\Delta c=0.450196\\ k_B$. However the idea of a deeper critical point singularity cannot be ruled out by present accuracy in neither theory nor experiment. The quantum phase transition consists of cosmic rays dominated by bosons for the low temperature phase E E_c$. The low temperature phase arises from those nuclei described by the usual and conventional collective boson models of nuclear physics. The high temperature phase is dominated by protons. The transition energy $E_c$ may be estimated in terms of the photo-disintegration of nuclei.

  9. Impurity binding energy for -doped quantum well structures

    Indian Academy of Sciences (India)

    V Tulupenko; C A Duque; R Demediuk; O Fomina; V Akimov; V Belykh; T Dmitrichenko; V Poroshin

    2014-10-01

    The binding energy of an impurity delta layer situated either in the centre or at the edge of a quantum well (QW) is theoretically considered for the example of -type Si0.8Ge0.2/Si/Si0.8Ge0.2 QW doped with phosphorus. Calculations are made for the case of not so big impurity concentrations, when impurity bands are not yet formed and it is still possible to treat impurity as isolated ones. It is shown on the base of self-consistent solution of Schrödinger, Poisson and electro-neutrality equations that impurity binding energy is dependent on the degree of impurity ionization and the most noticeably for the case of edge-doped QWs.

  10. Three-terminal energy harvester with coupled quantum dots.

    Science.gov (United States)

    Thierschmann, Holger; Sánchez, Rafael; Sothmann, Björn; Arnold, Fabian; Heyn, Christian; Hansen, Wolfgang; Buhmann, Hartmut; Molenkamp, Laurens W

    2015-10-01

    Rectification of thermal fluctuations in mesoscopic conductors is the key idea behind recent attempts to build nanoscale thermoelectric energy harvesters to convert heat into useful electric power. So far, most concepts have made use of the Seebeck effect in a two-terminal geometry, where heat and charge are both carried by the same particles. Here, we experimentally demonstrate the working principle of a new kind of energy harvester, proposed recently, using two capacitively coupled quantum dots. We show that, due to the novel three-terminal design of our device, which spatially separates the heat reservoir from the conductor circuit, the directions of charge and heat flow become decoupled. This enables us to manipulate the direction of the generated charge current by means of external gate voltages while leaving the direction of heat flow unaffected. Our results pave the way for a new generation of multi-terminal nanoscale heat engines.

  11. Does horizon entropy satisfy a Quantum Null Energy Conjecture?

    CERN Document Server

    Fu, Zicao

    2016-01-01

    A modern version of the idea that the area of event horizons gives $4G$ times an entropy is the Hubeny-Rangamani Causal Holographic Information (CHI) proposal for holographic field theories. Given a region $R$ of a holographic QFTs, CHI computes $A/4G$ on a certain cut of an event horizon in the gravitational dual. The result is naturally interpreted as a coarse-grained entropy. CHI is known to be finitely greater than the fine-grained Hubeny-Rangamani-Takayanagi (HRT) entropy when $\\partial R$ lies on a Killing horizon of the QFT spacetime, and in this context satisfies other non-trivial properties expected of an entropy. Here we present evidence that it also satisfies the quantum null energy condition (QNEC), which bounds the second derivative of the entropy of a quantum field theory on one side of a non-expanding null surface by the flux of stress-energy across the surface. In particular, we show CHI to satisfy the QNEC in 1+1 holographic CFTs when evaluated in states dual to conical defects in AdS$_3$. Th...

  12. A Model for High Energy Scattering in Quantum Gravity

    CERN Document Server

    Banks, T; Banks, Tom; Fischler, Willy

    1999-01-01

    We present a model for high energy two body scattering in a quantum theory of gravity. The model is applicable for center of mass energies higher than the relevant Planck scale. At impact parameters smaller than the Schwarzchild radius appropriate to the center of mass energy and total charge of the initial state, the cross section is dominated by an inelastic process in which a single large black hole is formed. The black hole then decays by Hawking radiation. The elastic cross section is highly suppressed at these impact parameters because of the small phase space for thermal decay into a high energy two body state. For very large impact parameter the amplitude is dominated by eikonalized single graviton exchange. At intermediate impact parameters the scattering is more complicated, but since the Schwarzchild radius grows with energy, we speculate that a more sophisticated eikonal calculation which uses the nonlinear classical solutions of the field equations may provide a good approximation at all larger i...

  13. Quantum Entanglement of Quantum Dot Spin Using Flying Qubits

    Science.gov (United States)

    2015-05-01

    SPDC photon is teleported to a single quantum dot spin by a projective measurement using a Hong Ou Mandel (HOM) interferometer. The SPDC source...photo diode B: Blue CW: Continuous wave DBR: Distributed Bragg reflector EOM: Electro-optics modulator H: Horizontal HOM: Hong-Ou- Mandel InAs

  14. Quantum Information An Introduction

    CERN Document Server

    Hayashi, Masahito

    2006-01-01

    Recently, quantum information theory has been developing through a fusion of results from various research fields. This requires that understanding of basic results on diverse topics, and derived from different disciplinary perspectives, is required for appreciating the overall picture. Intended to merge key topics from both the information-theoretic and quantum- mechanical viewpoints, this graduate-level textbook provides a unified viewpoint of quantum information theory and lucid explanations of those basic results, so that the reader fundamentally grasps advances and challenges. For example, advanced topics in quantum communication such as quantum teleportation, superdense coding, quantum state transmission (quantum error-correction), and quantum encryption especially benefit from this unified approach. Unlike earlier treatments, the text requires knowledge of only linear algebra, probability theory, and quantum mechanics, while it treats the topics of quantum hypothesis testing and the discrimination of q...

  15. Förster Resonance Energy Transfer between Quantum Dot Donors and Quantum Dot Acceptors

    Directory of Open Access Journals (Sweden)

    Kenny F. Chou

    2015-06-01

    Full Text Available Förster (or fluorescence resonance energy transfer amongst semiconductor quantum dots (QDs is reviewed, with particular interest in biosensing applications. The unique optical properties of QDs provide certain advantages and also specific challenges with regards to sensor design, compared to other FRET systems. The brightness and photostability of QDs make them attractive for highly sensitive sensing and long-term, repetitive imaging applications, respectively, but the overlapping donor and acceptor excitation signals that arise when QDs serve as both the donor and acceptor lead to high background signals from direct excitation of the acceptor. The fundamentals of FRET within a nominally homogeneous QD population as well as energy transfer between two distinct colors of QDs are discussed. Examples of successful sensors are highlighted, as is cascading FRET, which can be used for solar harvesting.

  16. Ag colloids and arrays for plasmonic non-radiative energy transfer from quantum dots to a quantum well

    CERN Document Server

    Murphy, Graham P; Higgins, Luke J; Karanikolas, Vasilios D; Wilson, Keith M; Coindreau, Jorge A Garcia; Zubialevich, Vitaly Z; Parbrook, Peter J; Bradley, A Louise

    2016-01-01

    Ag nanoparticles in the form of colloids and ordered arrays are used to demonstrate plasmon-mediated non-radiative energy transfer from quantum dots to quantum wells with varying top barrier thicknesses. Plasmon-mediated energy transfer efficiencies of up to ~25% are observed with the Ag colloids. The distance dependence of the plasmon-mediated energy transfer is found to follow the same d^{-4} dependence as the direct quantum dot to quantum well energy transfer. There is also evidence for an increase in the characteristic distance of the interaction, thus indicating that it follows a F\\"orster-like model with the Ag nanoparticle-quantum dot acting as an enhanced donor dipole. Ordered Ag nanoparticle arrays display plasmon-mediated energy transfer efficiencies up to ~21%. To explore the tunability of the array system, two arrays with different geometries are presented. It is demonstrated that changing the geometry of the array allows a transition from overall quenching of the acceptor quantum well emission to...

  17. Time as a Quantum Observable, Canonically Conjugated to Energy, and Foundations of Self-Consistent Time Analysis of Quantum Processes

    Directory of Open Access Journals (Sweden)

    V. S. Olkhovsky

    2009-01-01

    Full Text Available Recent developments are reviewed and some new results are presented in the study of time in quantum mechanics and quantum electrodynamics as an observable, canonically conjugate to energy. This paper deals with the maximal Hermitian (but nonself-adjoint operator for time which appears in nonrelativistic quantum mechanics and in quantum electrodynamics for systems with continuous energy spectra and also, briefly, with the four-momentum and four-position operators, for relativistic spin-zero particles. Two measures of averaging over time and connection between them are analyzed. The results of the study of time as a quantum observable in the cases of the discrete energy spectra are also presented, and in this case the quasi-self-adjoint time operator appears. Then, the general foundations of time analysis of quantum processes (collisions and decays are developed on the base of time operator with the proper measures of averaging over time. Finally, some applications of time analysis of quantum processes (concretely, tunneling phenomena and nuclear processes are reviewed.

  18. From quantum chemical formation free energies to evaporation rates

    Directory of Open Access Journals (Sweden)

    I. K. Ortega

    2012-01-01

    Full Text Available Atmospheric new particle formation is an important source of atmospheric aerosols. Large efforts have been made during the past few years to identify which molecules are behind this phenomenon, but the actual birth mechanism of the particles is not yet well known. Quantum chemical calculations have proven to be a powerful tool to gain new insights into the very first steps of particle formation. In the present study we use formation free energies calculated by quantum chemical methods to estimate the evaporation rates of species from sulfuric acid clusters containing ammonia or dimethylamine. We have found that dimethylamine forms much more stable clusters with sulphuric acid than ammonia does. On the other hand, the existence of a very deep local minimum for clusters with two sulfuric acid molecules and two dimethylamine molecules hinders their growth to larger clusters. These results indicate that other compounds may be needed to make clusters grow to larger sizes (containing more than three sulfuric acid molecules.

  19. Quantum information and computing

    CERN Document Server

    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

  20. Quantum Transfer Energy and Nonlocal Correlation in a Dimer with Time-Dependent Coupling Effect

    Science.gov (United States)

    El-Shishtawy, Reda M.; Berrada, K.; Haddon, Robert C.; Al-Hadeethi, Yas F.; Al-Heniti, Saleh H.; Raffah, Bahaaudin M.

    2017-02-01

    The presence of coherence phenomenon due to the interference of probability amplitude terms, is one of the most important features of quantum mechanics theory. Recent experiments show the presence of quantum processes whose coherence provided over suddenly large interval-time. In particular, photosynthetic mechanisms in light-harvesting complexes provide oscillatory behaviors in quantum mechanics due to quantum coherence. In this work, we investigate the coherent quantum transfer energy for a single-excitation and nonlocal correlation in a dimer system modelled by a two-level atom system with and without time-dependent coupling effect. We analyze and explore the required conditions that are feasible with real experimental realization for optimal transfer of quantum energy and generation of nonlocal quantum correlation. We show that the enhancement of the probability for a single-excitation transfer energy is greatly benefits from the combination of the energy detuning and time-dependent coupling effect. We investigate the presence of quantum correlations in the dimer using the entanglement of formation. We also find that the entanglement between the donor and acceptor is very sensitive to the physical parameters and it can be generated during the coherent energy transfer. On the other hand, we study the dynamical behavior of the quantum variance when performing a measurement on an observable of the density matrix operator. Finally, an interesting relationship between the transfer probability, entanglement and quantum variance is explored during the time evolution in terms of the physical parameters.

  1. Direct observation of electron-to-hole energy transfer in CdSe quantum dots.

    Science.gov (United States)

    Hendry, E; Koeberg, M; Wang, F; Zhang, H; de Mello Donegá, C; Vanmaekelbergh, D; Bonn, M

    2006-02-10

    We independently determine the subpicosecond cooling rates for holes and electrons in CdSe quantum dots. Time-resolved luminescence and terahertz spectroscopy reveal that the rate of hole cooling, following photoexcitation of the quantum dots, depends critically on the electron excess energy. This constitutes the first direct, quantitative measurement of electron-to-hole energy transfer, the hypothesis behind the Auger cooling mechanism proposed in quantum dots, which is found to occur on a 1 +/- 0.15 ps time scale.

  2. Quantum information theory mathematical foundation

    CERN Document Server

    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...

  3. Teleportation of one ququat encoded in single mode superposition of coherent states

    CERN Document Server

    Prakash, Hari

    2012-01-01

    Superposition of optical coherent states (SCS) Ket(plus/minus alpha), possessing opposite phases, plays an important role as qubits in quantum information processing tasks like quantum computation, teleportation, cryptography etc. and are of fundamental importance in testing quantum mechanics. Recently, ququats and qutrits defined in four and three dimensional (D) Hilbert space, respectively, have attracted much more attention as they present advantage in secure quantum communication and also in researches on the foundation of quantum mechanics. Here, we show that superposition of four non-orthogonal coherent states Ket(plus/minus alpha) and Ket(plus/minus i alpha), that are 90 degrees out of phase, can be employed for encoding one ququat defined in a 4D Hilbert space spanned by four newly defined multi-photonic states, Ket(alpha subscript j) with 4n+j numbers of photons, where, j= 0, 1, 2, 3. We propose a scheme which generates states Ket(alpha subscript j). When these states fall on a 50-50 beam splitter, t...

  4. Minimum energy surface required by quantum memory devices.

    Science.gov (United States)

    van Dam, Wim; Nguyen, Hieu D

    2013-06-21

    We address the question of what physical resources are required and sufficient to store classical information. While there is no lower bound on the required energy or space to store information, we find that there is a nonzero lower bound for the product P = of these two resources. Specifically, we prove that any physical system of mass m and d degrees of freedom that stores S bits of information will have a lower bound on the product P that is proportional to d2/m(exp(S/d) - 1)2. This result is obtained in a nonrelativistic, quantum mechanical setting, and it is independent of earlier thermodynamical results such as the Bekenstein bound on the entropy of black holes.

  5. Does horizon entropy satisfy a quantum null energy conjecture?

    Science.gov (United States)

    Fu, Zicao; Marolf, Donald

    2016-12-01

    A modern version of the idea that the area of event horizons gives 4G times an entropy is the Hubeny-Rangamani causal holographic information (CHI) proposal for holographic field theories. Given a region R of a holographic QFTs, CHI computes A/4G on a certain cut of an event horizon in the gravitational dual. The result is naturally interpreted as a coarse-grained entropy for the QFT. CHI is known to be finitely greater than the fine-grained Hubeny-Rangamani-Takayanagi (HRT) entropy when \\partial R lies on a Killing horizon of the QFT spacetime, and in this context satisfies other non-trivial properties expected of an entropy. Here we present evidence that it also satisfies the quantum null energy condition (QNEC), which bounds the second derivative of the entropy of a quantum field theory on one side of a non-expanding null surface by the flux of stress-energy across the surface. In particular, we show CHI to satisfy the QNEC in 1  +  1 holographic CFTs when evaluated in states dual to conical defects in AdS3. This surprising result further supports the idea that CHI defines a useful notion of coarse-grained holographic entropy, and suggests unprecedented bounds on the rate at which bulk horizon generators emerge from a caustic. To supplement our motivation, we include an appendix deriving a corresponding coarse-grained generalized second law for 1  +  1 holographic CFTs perturbatively coupled to dilaton gravity.

  6. Quantum mechanics/molecular mechanics dual Hamiltonian free energy perturbation.

    Science.gov (United States)

    Polyak, Iakov; Benighaus, Tobias; Boulanger, Eliot; Thiel, Walter

    2013-08-14

    The dual Hamiltonian free energy perturbation (DH-FEP) method is designed for accurate and efficient evaluation of the free energy profile of chemical reactions in quantum mechanical/molecular mechanical (QM/MM) calculations. In contrast to existing QM/MM FEP variants, the QM region is not kept frozen during sampling, but all degrees of freedom except for the reaction coordinate are sampled. In the DH-FEP scheme, the sampling is done by semiempirical QM/MM molecular dynamics (MD), while the perturbation energy differences are evaluated from high-level QM/MM single-point calculations at regular intervals, skipping a pre-defined number of MD sampling steps. After validating our method using an analytic model potential with an exactly known solution, we report a QM/MM DH-FEP study of the enzymatic reaction catalyzed by chorismate mutase. We suggest guidelines for QM/MM DH-FEP calculations and default values for the required computational parameters. In the case of chorismate mutase, we apply the DH-FEP approach in combination with a single one-dimensional reaction coordinate and with a two-dimensional collective coordinate (two individual distances), with superior results for the latter choice.

  7. Energy transfer processes in semiconductor quantum dots: bacteriorhodopsin hybrid system

    Science.gov (United States)

    Rakovich, Aliaksandra; Sukhanova, Alyona; Bouchonville, Nicolas; Molinari, Michael; Troyon, Michel; Cohen, Jacques H. M.; Rakovich, Yury; Donegan, John F.; Nabiev, Igor

    2009-05-01

    The potential impact of nanoscience on energy transfer processes in biomolecules was investigated on the example of a complex between fluorescent semiconductor nanocrystals and photochromic membrane protein. The interactions between colloidal CdTe quantum dots (QDs) and bacteriorhodopsin (bR) protein were studied by a variety of spectroscopic techniques, including integrated and time-resolved fluorescence spectroscopies, zeta potential and size measurement, and fluorescence correlation spectroscopy. QDs' luminescence was found to be strongly modulated by bacteriorhodopsin, but in a controllable way. Decreasing emission lifetimes and blue shifts in QDs' emission at increasing protein concentrations suggest that quenching occurs via Förster resonance energy transfer. On the other hand, concave Stern-Volmer plots and sigmoidal photoluminescence quenching curves imply that the self-assembling of NCs and bR exists, and the number of nanocrystals (NCs) per bacteriorhodopsin contributing to energy transfer can be determined from the inflection points of sigmoidal curves. This number was found to be highly dependent not only on the spectral overlap between NC emission and bR absorption bands, but also on nanocrystal surface charge. These results demonstrate the potential of how inorganic nanoscale materials can be employed to improve the generic molecular functions of biomolecules. The observed interactions between CdTe nanocrystals and bacteriorhodopsin can provide the basis for the development of novel functional materials with unique photonic properties and applications in areas such as all-optical switching, photovoltaics and data storage.

  8. Quantum energy decays and decoherence in discrete baths

    CERN Document Server

    Galiceanu, M D; Strunz, W

    2011-01-01

    The quantum average energy decay and the purity decay are studied for a system particle as a function of the number of constituents of a discrete bath model. The system particle is subjected to two distinct physical situations: the harmonic oscillator (HO) and the Morse potential. The environment (bath) is composed by a {\\it finite} number N of uncoupled HOs, characterizing the structured bath, which in the limit $N\\to\\infty$ is assumed to have an ohmic, sub-ohmic or super-ohmic spectral density. For very low values of N the mean energy and purity remain constant in time but starts to decay for intermediate values (10energy and coherence decay very fast and a Markovian dynamics is expected to occur. Wave packet dynamics is used ...

  9. Quantum information: primitive notions and quantum correlations

    CERN Document Server

    Scarani, Valerio

    2009-01-01

    This series of introductory lectures consists of two parts. In the first part, I rapidly review the basic notions of quantum physics and many primitives of quantum information (i.e. notions that one must be somehow familiar with in the field, like cloning, teleportation, state estimation...). The second part is devoted to a detailed introduction to the topic of quantum correlations, covering the evidence for failure of alternative theories, some aspects of the formalism of no-signaling probability distributions and some hints towards some current research topics in the field.

  10. Perfect Entanglement Teleportation via Two Parallel W State Channels

    Institute of Scientific and Technical Information of China (English)

    WANG Mei-Yu; YAN Feng-Li

    2011-01-01

    We present a scheme for perfectly teleporting a two-qubit entangled state via two parallel W state channels. The scheme consists of a positive operator valued measurement (POVM), classical communication and the corresponding local unitary operation. How to realize the POVM using unitary operation and projective measurement is explicitly designed.%@@ We present a scheme for perfectly teleporting a two-qubit entangled state via two parallel W state channels.The scheme consists of a positive operator valued measurement (POVM), classical communication and the corre- sponding local unitary operation.How to realize the POVM using unitary operation and projective measurement is explicitly designed.

  11. Teleportation of Atomic States for Atoms in a Lambda Configuration

    CERN Document Server

    Guerra, E S

    2004-01-01

    In this article we discuss a scheme of teleportation of atomic states making use of three-level lambda atoms. The experimental realization proposed makes use of cavity QED involving the interaction of Rydberg atoms with a micromaser cavity prepared in a coherent state. We start presenting a scheme to prepare atomic EPR states involving two-level atoms via the interaction of these atoms with a cavity. In our scheme the cavity and some atoms play the role of auxiliary systems used to achieve the teleportation.

  12. Teleportation of an Arbitrary Two-qubit State *

    Institute of Scientific and Technical Information of China (English)

    庞霖; 严瑛白; 金国藩; 韦辉; 郭履容

    2001-01-01

    A scheme to teleport an unknown two-qubit state from Alice (the sender) to Bob (the receiver) using two Einstein-Podolsky-Rosen (EPR) pairs is presented, each EPR pair being shared by both Alice and Bob. Firstly, Alice combines each of the two particles in the teleported state with an EPR particle and makes Bell state measurement on each combination. Then she transmits the outcomes of her measurements to Bob classically. According to Alice′s measurement results, Bob can perform appropriate unitary operations on his two EPR particles to retrieve the initial state.

  13. Probabilistic teleportation of an arbitrary pure state of two atoms

    Institute of Scientific and Technical Information of China (English)

    Yang Zhen-Biao; Wu Huai-Zhi; Su Wan-Jun

    2007-01-01

    In the context of microwave cavity QED, this paper proposes a new scheme for teleportation of an arbitrary pure state of two atoms. The scheme is very different from the previous ones which achieve the integrated state measurement,it deals in a probabilistic but simplified way. In the scheme, no additional atoms are involved and thus only two atoms are required to be detected. The scheme can also be used for the teleportation of arbitrary pure states of many atoms or two-mode cavities.

  14. Which Is Better at Predicting Quantum-Tunneling Rates: Quantum Transition-State Theory or Free-Energy Instanton Theory?

    Science.gov (United States)

    Zhang, Yanchuan; Stecher, Thomas; Cvitaš, Marko T; Althorpe, Stuart C

    2014-11-20

    Quantum transition-state theory (QTST) and free-energy instanton theory (FEIT) are two closely related methods for estimating the quantum rate coefficient from the free-energy at the reaction barrier. In calculations on one-dimensional models, FEIT typically gives closer agreement than QTST with the exact quantum results at all temperatures below the crossover to deep tunneling, suggesting that FEIT is a better approximation than QTST in this regime. Here we show that this simple trend does not hold for systems of greater dimensionality. We report tests on several collinear and three-dimensional reactions, in which QTST outperforms FEIT over a range of temperatures below crossover, which can extend down to half the crossover temperature (below which FEIT outperforms QTST). This suggests that QTST-based methods such as ring-polymer molecular dynamics (RPMD) may often give closer agreement with the exact quantum results than FEIT.

  15. A Feasible Scheme for Teleportation of Multi-atom Cat-like States in Thermal Cavities

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    An experimentally feasible scheme for implementing teleportation of multi-atom cat-like states in cavity QED is proposed. In the scheme the atoms interact simultaneously with a highly detuned cavity mode and are driven by a strong classical field, and the atomic state evolution is independent of cavity field state. Thus the scheme is insensitive to both the cavity decay and the thermal field, which is of importance from the experimental point of view. All the orthogonal and complete multi-atom GHZ states can be exactly distinguished only by one step, so our scheme can also be used for other purposes such as dense coding using multi-atom GHZ states as quantum channels.

  16. A study of Quantum Correlations in Open Quantum Systems

    CERN Document Server

    Chakrabarty, Indranil; Siddharth, Nana

    2010-01-01

    In this work, we study quantum correlations in mixed states. The states studied are modelled by a two-qubit system interacting with its environment via a quantum nondemolition (purely dephasing) as well as dissipative type of interaction. The entanglement dynamics of this two qubit system is analyzed and the existence of entangled states which do not violate Bell's inequality, but can still be useful as a potential resource for teleportation are reported. In addition, a comparative study of various measures of quantum correlations, like Concurrence, Bell's inequality, Discord and Teleportation fidelity, is made on these states, generated by the above evolutions. Interestingly, examples are found, of states, where entanglement is vanishing, but discord is non-vanishing, bringing out the fact that entanglement is a subset of quantum correlations.

  17. Quantum thermodynamic processes energy and information flow at the nanoscale

    CERN Document Server

    Mahler, Guenter

    2015-01-01

    The point of departure of this book is a triad of themes: information theory, thermodynamics, and quantum mechanics. These are related: thermodynamics and quantum mechanics form the basis of quantum thermodynamics; information and quantum mechanics underly, inter alia, the notorious quantum measurement problem; and information and thermodynamics have much to say about control limits in the tension between micro- and macro-descriptions.Why does the world around us typically look thermal-from cosmology down to individual embedded spins? Do informational measures constitute additional (independen

  18. Cavity quantum networks for quantum information processing in decoherence-free subspace

    Institute of Scientific and Technical Information of China (English)

    Hua WEI; Zhi-jiao DENG; Wan-li YANG; Fei ZHOU

    2009-01-01

    We give a brief review on the quantum infor- mation processing in decoherence-free subspace (DFS). We show how to realize the initialization of the entangled quantum states, information transfer and teleportation of quantum states, two-qubit Grover search and how to construct the quantum network in DFS, within the cav- ity QED regime based on a cavity-assisted interaction by single-photon pulses.

  19. Tuning the Emission Energy of Chemically Doped Graphene Quantum Dots

    Directory of Open Access Journals (Sweden)

    Noor-Ul-Ain

    2016-11-01

    Full Text Available Tuning the emission energy of graphene quantum dots (GQDs and understanding the reason of tunability is essential for the GOD function in optoelectronic devices. Besides material-based challenges, the way to realize chemical doping and band gap tuning also pose a serious challenge. In this study, we tuned the emission energy of GQDs by substitutional doping using chlorine, nitrogen, boron, sodium, and potassium dopants in solution form. Photoluminescence data obtained from (Cl- and N-doped GQDs and (B-, Na-, and K-doped GQDs, respectively exhibited red- and blue-shift with respect to the photoluminescence of the undoped GQDs. X-ray photoemission spectroscopy (XPS revealed that oxygen functional groups were attached to GQDs. We qualitatively correlate red-shift of the photoluminescence with the oxygen functional groups using literature references which demonstrates that more oxygen containing groups leads to the formation of more defect states and is the reason of observed red-shift of luminescence in GQDs. Further on, time resolved photoluminescence measurements of Cl- and N-GQDs demonstrated that Cl substitution in GQDs has effective role in radiative transition whereas in N-GQDs leads to photoluminescence (PL quenching with non-radiative transition to ground state. Presumably oxidation or reduction processes cause a change of effective size and the bandgap.

  20. Energy levels and quantum states of [Leu]enkephalin conformations based on theoretical and experimental investigations

    Energy Technology Data Exchange (ETDEWEB)

    Abdali, Salim; Jensen, Morten O; Bohr, Henrik [Quantum Protein Centre (QUP), Department of Physics, Bldg. 309, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark)

    2003-05-14

    This paper describes a theoretical and experimental study of [Leu]enkephalin conformations with respect to the quantum states 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 vibrational modes to the different conformations. The energy landscape of the conformations is reported as a function of a Hamming distance in Ramachandran space. Molecular dynamics simulations reveal a pronounced stability of the so-called single-bend low-energy conformation, which supports the derived quantum picture of this peptide.

  1. Energy levels and quantum states of [Leu]enkephalin conformations based on theoretical and experimental investigations

    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...... vibrational modes to the different conformations. The energy landscape of the conformations is reported as a function of a Hamming distance in Ramachandran space. Molecular dynamics simulations reveal a pronounced stability of the so-called single-bend low-energy conformation, which supports the derived...... quantum picture of this peptide....

  2. 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.)

  3. Testing Quantum Devices: Practical Entanglement Verification in Bipartite Optical Systems

    OpenAIRE

    Häseler, Hauke; Moroder, Tobias; Lütkenhaus, Norbert

    2007-01-01

    We present a method to test quantum behavior of quantum information processing devices, such as quantum memories, teleportation devices, channels and quantum key distribution protocols. The test of quantum behavior can be phrased as the verification of effective entanglement. Necessary separability criteria are formulated in terms of a matrix of expectation values in conjunction with the partial transposition map. Our method is designed to reduce the resources for entanglement verification. A...

  4. Coherent Communication with Continuous Quantum Variables

    CERN Document Server

    Wilde, M M; Krovi, H; Brun, Todd A.; Krovi, Hari; Wilde, Mark M.

    2006-01-01

    The coherent bit (cobit) channel is a resource intermediate between classical communication and quantum communication. The cobit channel produces coherent versions of the teleportation and superdense coding protocols. We extend the cobit channel to the continuous variables of quantum optics. We provide a general definition of the ``coherent nat'' (conat) channel when only finite-squeezing resources are available. Coherent teleportation provides sufficient conditions and coherent superdense coding provides necessary conditions for a channel to be a finite-squeezing approximation to an ideal conat channel. We illustrate several protocols that use both a position-quadrature and a momentum-quadrature conat channel. Finally, we address the reversibility of coherent teleportation and coherent superdense coding with only finite-squeezing resources.

  5. Teleportation of Cavity Field States via Cavity QED

    CERN Document Server

    Guerra, E S

    2004-01-01

    In this article we discuss two schemes of teleportation of cavity field states. In the first scheme we consider cavities prepared in a coherent state and in the second scheme we consider cavities prepared in a superposition of zero and one Fock states.

  6. Teleportation of atomic states with a weak coherent cavity field

    Institute of Scientific and Technical Information of China (English)

    Zheng Shi-Biao

    2005-01-01

    A scheme is proposed for the teleportation of an unknown atomic state. The scheme is based on the resonant interaction of atoms with a coherent cavity field. The mean photon-number of the cavity field is much smaller than one and thus the cavity decay can be effectively suppressed. Another adwntage of the scheme is that only one cavity is required.

  7. Teleportation of an Unknown Atomic State via Adiabatic Passage

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    We propose a scheme for teleporting an unknown atomic state via adiabatic passage. Taking advantage of adiabatic passage, the atom has no probability of being excited and thus the atomic spontaneous emission is suppressed.We also show that the fidelity can reach 1 under certain condition.

  8. Geometric effects on energy states of a hydrogenic impurity in multilayered spherical quantum dot

    Energy Technology Data Exchange (ETDEWEB)

    Boz, Figen Karaca, E-mail: figenkaraca@mynet.com [Department of Physics, Trakya University, Edirne 22030 (Turkey); Aktas, Saban [Department of Physics, Trakya University, Edirne 22030 (Turkey); Bilekkaya, Abdullah [Department of Electronics, Trakya University Edirne Vocational College of Technical Sciences, Edirne 22100 (Turkey); Okan, Sevket Erol [Department of Physics, Trakya University, Edirne 22030 (Turkey)

    2009-04-15

    The energy states of a hydrogenic impurity, located at the center of a multilayered spherical quantum dot, are calculated as functions of the barrier thickness and the inner dot thickness by using a fourth-order Runge-Kutta method. It is shown that the method is able to calculate all the energy states for any potential profile in the dot. Also, the binding energies show dramatic changes in comparison with those of single spherical quantum dots.

  9. Electron-lattice energy exchange in metal nanoparticles. Quantum-kinetic and classical approaches

    OpenAIRE

    Tomchuk, Petro; Bilotsky, Yevgen

    2014-01-01

    We obtained the electron-lattice energy transfer constant in metal nanoparticles (MN), in quantum-mechanical and classical approach using the deformation potential Bardeen-Shockley and found the changes of the electron-lattice energy exchange (due to the finite size MN) in the quantum kinetic approach caused by the discrete phonon spectrum. The condition when the discrete phonon spectrum could be observed via the electron-phonon energy exchange has been obtained. It was shown that the classic...

  10. Crushing runtimes in adiabatic quantum computation with Energy Landscape Manipulation (ELM): Application to Quantum Factoring

    Science.gov (United States)

    Dattani, Nike; Tanburn, Richard; Lunt, Oliver

    We introduce two methods for speeding up adiabatic quantum computations by increasing the energy between the ground and first excited states. Our methods are even more general. They can be used to shift a Hamiltonian's density of states away from the ground state, so that fewer states occupy the low-lying energies near the minimum, hence allowing for faster adiabatic passages to find the ground state with less risk of getting caught in an undesired low-lying excited state during the passage. Even more generally, our methods can be used to transform a discrete optimization problem into a new one whose unique minimum still encodes the desired answer, but with the objective function's values forming a different landscape. Aspects of the landscape such as the objective function's range, or the values of certain coefficients, or how many different inputs lead to a given output value, can be decreased *or* increased. One of the many examples for which these methods are useful is in finding the ground state of a Hamiltonian using NMR. We apply our methods to an AQC algorithm for integer factorization, and the first method reduces the maximum runtime in our example by up to 754%, and the second method reduces the maximum runtime of another example by up to 250%.

  11. Contract Signature Using Quantum Information

    CERN Document Server

    De Sousa, P B M; Ramos, Rubens Viana; Sousa, Paulo Benicio Melo de

    2006-01-01

    This paper describes how to perform contract signature in a fair way using quantum information. The protocol proposed permits two partners, users of a communication network, to exchange their signatures with non-repudiation. For this, we assume that there is a trustable arbitrator, responsible for the authentication of the signers and that performs a central task in a quantum teleportation protocol of the XOR function between two classical bits.

  12. Calculations of Solvation Free Energy through Energy Reweighting from Molecular Mechanics to Quantum Mechanics.

    Science.gov (United States)

    Jia, Xiangyu; Wang, Meiting; Shao, Yihan; König, Gerhard; Brooks, Bernard R; Zhang, John Z H; Mei, Ye

    2016-02-09

    In this work, the solvation free energies of 20 organic molecules from the 4th Statistical Assessment of the Modeling of Proteins and Ligands (SAMPL4) have been calculated. The sampling of phase space is carried out at a molecular mechanical level, and the associated free energy changes are estimated using the Bennett Acceptance Ratio (BAR). Then the quantum mechanical (QM) corrections are computed through the indirect Non-Boltzmann Bennett's acceptance ratio (NBB) or the thermodynamics perturbation (TP) method. We show that BAR+TP gives a minimum analytic variance for the calculated solvation free energy at the Gaussian limit and performs slightly better than NBB in practice. Furthermore, the expense of the QM calculations in TP is only half of that in NBB. We also show that defining the biasing potential as the difference of the solute-solvent interaction energy, instead of the total energy, can converge the calculated solvation free energies much faster but possibly to different values. Based on the experimental solvation free energies which have been published before, it is discovered in this study that BLYP yields better results than MP2 and some other later functionals such as B3LYP, M06-2X, and ωB97X-D.

  13. Problems and solutions in quantum computing and quantum information

    CERN Document Server

    Steeb, Willi-Hans

    2012-01-01

    Quantum computing and quantum information are two of the fastest growing and most exciting research fields in physics. Entanglement, teleportation and the possibility of using the non-local behavior of quantum mechanics to factor integers in random polynomial time have also added to this new interest. This book supplies a huge collection of problems in quantum computing and quantum information together with their detailed solutions, which will prove to be invaluable to students as well as researchers in these fields. All the important concepts and topics such as quantum gates and quantum circuits, product Hilbert spaces, entanglement and entanglement measures, deportation, Bell states, Bell inequality, Schmidt decomposition, quantum Fourier transform, magic gate, von Neumann entropy, quantum cryptography, quantum error corrections, number states and Bose operators, coherent states, squeezed states, Gaussian states, POVM measurement, quantum optics networks, beam splitter, phase shifter and Kerr Hamilton opera...

  14. Quantum dot-dye hybrid systems for energy transfer applications

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Ting

    2010-07-01

    In this thesis, we focus on the preparation of energy transfer-based quantum dot (QD)-dye hybrid systems. Two kinds of QD-dye hybrid systems have been successfully synthesized: QD-silica-dye and QD-dye hybrid systems. In the QD-silica-dye hybrid system, multishell CdSe/CdS/ZnS QDs were adsorbed onto monodisperse Stoeber silica particles with an outer silica shell of thickness 2-24 nm containing organic dye molecules (Texas Red). The thickness of this dye layer has a strong effect on the total sensitized acceptor emission, which is explained by the increase in the number of dye molecules homogeneously distributed within the silica shell, in combination with an enhanced surface adsorption of QDs with increasing dye amount. Our conclusions were underlined by comparison of the experimental results with Monte-Carlo simulations, and by control experiments confirming attractive interactions between QDs and Texas Red freely dissolved in solution. New QD-dye hybrid system consisting of multishell QDs and organic perylene dyes have been synthesized. We developed a versatile approach to assemble extraordinarily stable QD-dye hybrids, which uses dicarboxylate anchors to bind rylene dyes to QD. This system yields a good basis to study the energy transfer between QD and dye because of its simple and compact design: there is no third kind of molecule linking QD and dye; no spacer; and the affinity of the functional group to the QD surface is strong. The FRET signal was measured for these complexes as a function of both dye to QD ratio and center-to-center distance between QD and dye by controlling number of covered ZnS layers. Data showed that fluorescence resonance energy transfer (FRET) was the dominant mechanism of the energy transfer in our QD-dye hybrid system. FRET efficiency can be controlled by not only adjusting the number of dyes on the QD surface or the QD to dye distance, but also properly choosing different dye and QD components. Due to the strong stability, our QD

  15. Energy dissipation dataset for reversible logic gates in quantum dot-cellular automata.

    Science.gov (United States)

    Bahar, Ali Newaz; Rahman, Mohammad Maksudur; Nahid, Nur Mohammad; Hassan, Md Kamrul

    2017-02-01

    This paper presents an energy dissipation dataset of different reversible logic gates in quantum-dot cellular automata. The proposed circuits have been designed and verified using QCADesigner simulator. Besides, the energy dissipation has been calculated under three different tunneling energy level at temperature T=2 K. For estimating the energy dissipation of proposed gates; QCAPro tool has been employed.

  16. Modeling the cooperative energy transfer dynamics of quantum cutting for solar cells

    NARCIS (Netherlands)

    Rabouw, Freddy T.; Meijerink, Andries

    2015-01-01

    Cooperative energy transfer (ET) is a quantum cutting (or downconversion) process where a luminescent center splits its excited state energy in two by simultaneous transfer to two nearby acceptor centers, thus yielding two low-energy photons for each high-energy photon absorbed. It has the potential

  17. Quantum weirdness

    CERN Document Server

    Mullin, William J

    2017-01-01

    Quantum mechanics allows a remarkably accurate description of nature and powerful predictive capabilities. The analyses of quantum systems and their interpretation lead to many surprises, for example, the ability to detect the characteristics of an object without ever touching it in any way, via "interaction-free measurement," or the teleportation of an atomic state over large distances. The results can become downright bizarre. Quantum mechanics is a subtle subject that usually involves complicated mathematics -- calculus, partial differential equations, etc., for complete understanding. Most texts for general audiences avoid all mathematics. The result is that the reader misses almost all deep understanding of the subject, much of which can be probed with just high-school level algebra and trigonometry. Thus, readers with that level of mathematics can learn so much more about this fundamental science. The book starts with a discussion of the basic physics of waves (an appendix reviews some necessary class...

  18. Open quantum physics and environmental heat conversion into usable energy

    CERN Document Server

    Stefanescu, Eliade

    2014-01-01

    A Quantum system can be viewed as a larger closed system comprising of two components: an open quantum system and its surrounding environment. These two components interact with each other, and in the realm of theoretical physics, this interaction cannot be neglected. This eBook A Quantum system can be viewed as a larger closed system comprising of two components: an open quantum system and its surrounding environment. These two components interact with each other, and in the realm of theoretical physics, this interaction cannot be neglected. This eBook explains mathematical and statistical co

  19. Young Quantum Meetings

    CERN Document Server

    Aerts, Sven; Ronde, Christian de; Probing the Meaning of Quantum Mechanics : Physical, Philosophical, and Logical Perspectives

    2014-01-01

    This book provides a new original perspective on one of the most fascinating and important open questions in science: What is quantum mechanics talking about? Quantum theory is perhaps our best confirmed physical theory. However, in spite of its great empirical effectiveness and the subsequent technological developments that it gave rise to in the 20th century, from the interpretation of the periodic table of elements to CD players, holograms and quantum state teleportation, it stands even today without a universally accepted interpretation. The novelty of the book comes from the multiple view

  20. Explorations in quantum computing

    CERN Document Server

    Williams, Colin P

    2011-01-01

    By the year 2020, the basic memory components of a computer will be the size of individual atoms. At such scales, the current theory of computation will become invalid. ""Quantum computing"" is reinventing the foundations of computer science and information theory in a way that is consistent with quantum physics - the most accurate model of reality currently known. Remarkably, this theory predicts that quantum computers can perform certain tasks breathtakingly faster than classical computers -- and, better yet, can accomplish mind-boggling feats such as teleporting information, breaking suppos

  1. Energy Spectra of Excitons Bound to a Neutral Acceptor in Quantum Dots

    Institute of Scientific and Technical Information of China (English)

    XIE Wen-Fang

    2004-01-01

    The energy spectra of the ground state for an exciton (X) trapped by a neutral acceptor (A0) in a quantum dot with a parabolic confinement have been calculated as a function of the electron-to-hole mass ratio σ by using the hyperspherical coordinates. We find that the (A0, X) complex confined in a quantum dot has in general a larger binding energy than those in a two-dimensional quantum well and a three-dimensional bulk semiconductor, and the binding energy decreases with the increase of the electron-to-hole mass ratio.

  2. On the binding energies of excitons in polar quantum well structures in a weak electric field

    Institute of Scientific and Technical Information of China (English)

    Wu Yun-Feng; Liang Xi-Xia; K. K. Bajaj

    2005-01-01

    The binding energies of excitons in quantum well structures subjected to an applied uniform electric field by taking into account the exciton longitudinal optical phonon interaction is calculated. The binding energies and corresponding Stark shifts for Ⅲ-Ⅴ and Ⅱ-Ⅵ compound semiconductor quantum well structures have been numerically computed.The results for GaAs/AlGaAs and ZnCdSe/ZnSe quantum wells are given and discussed. Theoretical results show that the exciton-phonon coupling reduces both the exciton binding energies and the Stark shifts by screening the Coulomb interaction. This effect is observable experimentally and cannot be neglected.

  3. Breakdown of the equivalence between active gravitational mass and energy for a quantum body

    CERN Document Server

    Lebed, Andrei G

    2016-01-01

    We determine active gravitational mass operator of the simplest composite quantum body - a hydrogen atom - within the semiclassical approach to the Einstein equation for a gravitational field. We show that the expectation value of the mass is equivalent to energy for stationary quantum states. On the other hand, it occurs that, for quantum superpositions of stationary states with constant expectation values of energy, the expectation values of the gravitational mass exhibit time-dependent oscillations. This breaks the equivalence between active gravitational mass and energy and can be observed as a macroscopic effect for a macroscopic ensemble of coherent quantum states of the atoms. The corresponding experiment could be the first direct observation of quantum effects in General Relativity.

  4. Quantum entanglement and teleportation in pulsed cavity optomechanics

    Energy Technology Data Exchange (ETDEWEB)

    Hofer, Sebastian G. [Vienna Center for Quantum Science and Technology, Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna (Austria); Institute for Theoretical Physics, Institute for Gravitational Physics, Leibniz University Hannover, Callinstrasse 38, 30167 Hannover (Germany); Wieczorek, Witlef; Aspelmeyer, Markus [Vienna Center for Quantum Science and Technology, Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna (Austria); Hammerer, Klemens [Institute for Theoretical Physics, Institute for Gravitational Physics, Leibniz University Hannover, Callinstrasse 38, 30167 Hannover (Germany)

    2011-11-15

    Entangling a mechanical oscillator with an optical mode is an enticing and yet a very challenging goal in cavity optomechanics. Here we consider a pulsed scheme to create Einstein-Podolsky-Rosen-type entanglement between a traveling-wave light pulse and a mechanical oscillator. The entanglement can be verified unambiguously by a pump-probe sequence of pulses. In contrast to schemes that work in a steady-state regime under a continuous-wave drive, this protocol is not subject to stability requirements that normally limit the strength of achievable entanglement. We investigate the protocol's performance under realistic conditions, including mechanical decoherence, in full detail. We discuss the relevance of a high mechanical Qf product for entanglement creation and provide a quantitative statement on which magnitude of the Qf product is necessary for a successful realization of the scheme. We determine the optimal parameter regime for its operation and show it to work in current state-of-the-art systems.

  5. About Dark Energy and Dark Matter in a Three-Dimensional Quantum Vacuum Model

    Science.gov (United States)

    Fiscaletti, Davide

    2016-10-01

    A model of a three-dimensional quantum vacuum based on Planck energy density as a universal property of a granular space is suggested. The possibility to provide an unifying explanation of dark matter and dark energy as phenomena linked with the fluctuations of the three-dimensional quantum vacuum is explored. The changes and fluctuations of the quantum vacuum energy density generate a curvature of space-time similar to the curvature produced by a "dark energy" density. The formation of large scale structures in the universe associated to the flattening of the orbital speeds of the spiral galaxies can be explained in terms of primary fluctuations of the quantum vacuum energy density without attracting the idea of dark matter.

  6. Conversion efficiency of an energy harvester based on resonant tunneling through quantum dots with heat leakage

    Science.gov (United States)

    Kano, Shinya; Fujii, Minoru

    2017-03-01

    We study the conversion efficiency of an energy harvester based on resonant tunneling through quantum dots with heat leakage. Heat leakage current from a hot electrode to a cold electrode is taken into account in the analysis of the harvester operation. Modeling of electrical output indicates that a maximum heat leakage current is not negligible because it is larger than that of the heat current harvested into electrical power. A reduction of heat leakage is required in this energy harvester in order to obtain efficient heat-to-electrical conversion. Multiple energy levels of a quantum dot can increase the output power of the harvester. Heavily doped colloidal semiconductor quantum dots are a possible candidate for a quantum-dot monolayer in the energy harvester to reduce heat leakage, scaling down device size, and increasing electrical output via multiple discrete energy levels.

  7. Testing Loop Quantum Gravity and Electromagnetic Dark Energy in Superconductors

    CERN Document Server

    de Matos, Clovis Jacinto

    2008-01-01

    In 1989 Cabrera and Tate reported an anomalous excess of mass of the Cooper pairs in rotating thin Niobium rings. So far, this experimental result never received a proper theoretical explanation in the context of superconductor's physics. In the present work we argue that what Cabrera and Tate interpreted as an anomalous excess of mass can also be associated with a deviation from the classical gravitomagnetic Larmor theorem due to the presence of dark energy in the superconductor, as well as with the discrete structure of the area of the superconducting Niobium ring as predicted by Loop Quantum Gravity. From Cabrera and Tate measurements we deduce that the quantization of spacetime in superconducting circular rings occurs at the Planck-Einstein scale $l_{PE} = (\\hbar G/c^3 \\Lambda)^{1/4}\\sim 3.77\\times 10 ^{-5} m$, instead of the Planck scale $l_{P} =(\\hbar G / c^3)^{1/2}=1.61 \\times 10 ^{-35} m$, with an Immirzi parameter which depends on the specific critical temperature of the superconducting material and ...

  8. Direct Observation of Electron-to-Hole Energy Transfer in CdSe Quantum Dots

    NARCIS (Netherlands)

    Hendry, E.; Koeberg, M.; Wang, F.; Zhang, H.; de Mello Donega, C.; Vanmaekelbergh, D.; Bonn, M.

    2006-01-01

    We independently determine the subpicosecond cooling rates for holes and electrons in CdSe quantum dots. Time-resolved luminescence and terahertz spectroscopy reveal that the rate of hole cooling, following photoexcitation of the quantum dots, depends critically on the electron excess energy. This c

  9. Interqubit coupling mediated by a high-excitation-energy quantum object

    NARCIS (Netherlands)

    Ashhab, S.; Niskanen, A.O.; Harrabi, K.; Nakamura, Y.; Picot, T.; De Groot, P.C.; Harmans, C.J.P.M.; Mooij, J.E.; Nori, F.

    2008-01-01

    We consider a system composed of two qubits and a high excitation energy quantum object used to mediate coupling between the qubits. We treat the entire system quantum mechanically and analyze the properties of the eigenvalues and eigenstates of the total Hamiltonian. After reproducing well known re

  10. Covariant methods for calculating the low-energy effective action in quantum field theory and quantum gravity

    CERN Document Server

    Avramidi, I G

    1994-01-01

    We continue the development of the effective covariant methods for calculating the heat kernel and the one-loop effective action in quantum field theory and quantum gravity. The status of the low-energy approximation in quantum gauge theories and quantum gravity is discussed in detail on the basis of analyzing the local Schwinger - De Witt expansion. It is argued that the low-energy limit, when defined in a covariant way, should be related to background fields with covariantly constant curvature, gauge field strength and potential. Some new approaches for calculating the low-energy heat kernel assuming a covariantly constant background are proposed. The one-loop low-energy effective action in Yang-Mills theory in flat space with arbitrary compact simple gauge group and arbitrary matter on a covariantly constant background is calculated. The stability problem of the chromomagnetic (Savvidy-type) vacuum is analyzed. It is shown, that this type of vacuum structure can be stable only in the case when more than on...

  11. Imaging and Manipulating Energy Transfer Among Quantum Dots at Individual Dot Resolution.

    Science.gov (United States)

    Nguyen, Duc; Nguyen, Huy A; Lyding, Joseph W; Gruebele, Martin

    2017-06-27

    Many processes of interest in quantum dots involve charge or energy transfer from one dot to another. Energy transfer in films of quantum dots as well as between linked quantum dots has been demonstrated by luminescence shift, and the ultrafast time-dependence of energy transfer processes has been resolved. Bandgap variation among dots (energy disorder) and dot separation are known to play an important role in how energy diffuses. Thus, it would be very useful if energy transfer could be visualized directly on a dot-by-dot basis among small clusters or within films of quantum dots. To that effect, we report single molecule optical absorption detected by scanning tunneling microscopy (SMA-STM) to image energy pooling from donor into acceptor dots on a dot-by-dot basis. We show that we can manipulate groups of quantum dots by pruning away the dominant acceptor dot, and switching the energy transfer path to a different acceptor dot. Our experimental data agrees well with a simple Monte Carlo lattice model of energy transfer, similar to models in the literature, in which excitation energy is transferred preferentially from dots with a larger bandgap to dots with a smaller bandgap.

  12. Energy transfer in organic multilayer quantum well structure and its application to OLEDs

    Institute of Scientific and Technical Information of China (English)

    ZHAO De-wei; SONG Shu-fang; ZHAO Su-ling; XU Zheng

    2007-01-01

    We fabricate a series of samples and OLEDs with organic multilayer quantum well structure, which consist of alternate PBD and Alq3. Both PBD and Alq3 are electron-transporting materials, and PBD is used as potential barrier layer, while Alq3 is used as potential well layer and emitting layer. Compared with double-layer structure, the luminescent characteristics of organic samples and diodes with quantum well structure are investigated and the quantum well structure helps the energy transfer between well layer and barrier layer. The quantum well structure makes carriers disperse in the different well layers and then increases the number of excitons to enhance the efficiency of the recombination.

  13. Equivalence between entanglement and the optimal fidelity of continuous variable teleportation.

    Science.gov (United States)

    Adesso, Gerardo; Illuminati, Fabrizio

    2005-10-07

    We devise the optimal form of Gaussian resource states enabling continuous-variable teleportation with maximal fidelity. We show that a nonclassical optimal fidelity of N-user teleportation networks is necessary and sufficient for N-party entangled Gaussian resources, yielding an estimator of multipartite entanglement. The entanglement of teleportation is equivalent to the entanglement of formation in a two-user protocol, and to the localizable entanglement in a multiuser one. Finally, we show that the continuous-variable tangle, quantifying entanglement sharing in three-mode Gaussian states, is defined operationally in terms of the optimal fidelity of a tripartite teleportation network.

  14. Teleportation of a Coherent Superposition State Via a nonmaximally Entangled Coherent Xhannel

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    @@ We investigate the problemm of teleportation of a superposition coherent state with nonmaximally entangled coherent channel. Two strategies are considered to complete the task. The first one uses entanglement concentration to purify the channel to a maximally entangled one. The second one teleports the state through the nonmaximally entangled coherent channel directly. We find that the probabilities of successful teleportations for the two strategies are depend on the amplitudes of the coherent states and the mean fidelity of teleportation using the first strategy is always less than that of the second strategy.

  15. Resonant electronic excitation energy transfer by Dexter mechanism in the quantum dot system

    Science.gov (United States)

    Samosvat, D. M.; Chikalova-Luzina, O. P.; Vyatkin, V. M.; Zegrya, G. G.

    2016-11-01

    In present work the energy transfer between quantum dots by the exchange (Dexter) mechanism is analysed. The interdot Coulomb interaction is taken into consideration. It is assumed that the quantum dot-donor and the quantum dot-acceptor are made from the same compound A3B5 and embedded in the matrix of other material creating potential barriers for electron and holes. The dependences of the energy transfer rate on the quantum-dot system parameters are found using the Kane model that provides the most adequate description spectra of semiconductors A3B5. Numerical calculations show that the rate of the energy transfer by Dexter mechanism is comparable to the rate of the energy transfer by electrostatic mechanism at the distances approaching to the contact ones.

  16. Long-Distance Quantum Communication with Neutral Atoms

    CERN Document Server

    Razavi, M; Razavi, Mohsen; Shapiro, Jeffrey H.

    2005-01-01

    The architecture proposed by Duan, Lukin, Cirac, and Zoller (DLCZ) for long-distance quantum communication with atomic ensembles is analyzed. Its fidelity and throughput in entanglement distribution, entanglement swapping, and quantum teleportation is derived within a framework that accounts for multiple excitations in the ensembles as well as loss and asymmetries in the channel. The DLCZ performance metrics that are obtained are compared to the corresponding results for the trapped-atom quantum communication architecture that has been proposed by a team from the Massachusetts Institute of Technology and Northwestern University (MIT/NU). Both systems are found to be capable of high-fidelity entanglement distribution. However, the DLCZ scheme only provides conditional teleportation and repeater operation, whereas the MIT/NU architecture affords full Bell-state measurements on its trapped atoms. Moreover, it is shown that achieving unity conditional fidelity in DLCZ teleportation and repeater operation requires...

  17. Ultrafast Long-Distance Quantum Communication with Static Linear Optics

    Science.gov (United States)

    Ewert, Fabian; Bergmann, Marcel; van Loock, Peter

    2016-11-01

    We propose a projection measurement onto encoded Bell states with a static network of linear optical elements. By increasing the size of the quantum error correction code, both Bell measurement efficiency and photon-loss tolerance can be made arbitrarily high at the same time. As a main application, we show that all-optical quantum communication over large distances with communication rates similar to those of classical communication is possible solely based on local state teleportations using optical sources of encoded Bell states, fixed arrays of beam splitters, and photon detectors. As another application, generalizing state teleportation to gate teleportation for quantum computation, we find that in order to achieve universality the intrinsic loss tolerance must be sacrificed and a minimal amount of feedforward has to be added.

  18. Advanced Visual Quantum Mechanics

    CERN Document Server

    Thaller, Bernd

    2005-01-01

    Advanced Visual Quantum Mechanics is a systematic effort to investigate and to teach quantum mechanics with the aid of computer-generated animations. It is a self-contained textbook that combines selected topics from atomic physics (spherical symmetry, the hydrogen atom, and particles with spin) with an introduction to quantum information theory (qubits, EPR paradox, teleportation, quantum computers). It explores relativistic quantum mechanics and the strange behavior of Dirac equation solutions. A series of appendices covers important topics from perturbation and scattering theory. The book places an emphasis on ideas and concepts, with a fair to moderate amount of mathematical rigor. Though this book stands alone, it can also be paired with Thaller Visual Quantum Mechanics to form a comprehensive course in quantum mechanics. The software for the first book earned the European Academic Software Award 2000 for outstanding innovation in its field.

  19. ENERGY LEVEL DETERMINATION AND PERFORMANCE ANALYSIS OF QUANTUM DOT PHOTO DETECTOR

    Directory of Open Access Journals (Sweden)

    M. Madheswaran

    2013-09-01

    Full Text Available The theoretical estimation of dark and illumination characteristics of InGaAs quantum dot photo detector is developed and presented in this paper. The exact potential and energy profile of the Quantum Dot is computed by obtaining the solution of 3D Poisson and Schrodinger equations using Homotopy analysis. The dark current, photo current, responsivity, detectivity and efficiency of the model are calculated by considering the structural parameters Quantum Dot density, applied voltage, length of quantum dot array, number of quantum dot array, light intensity and temperature. The results obtained show that the dark current and photo current are strongly influenced by Quantum Dot density and applied voltage. The developed model is purely physics based one and overcomes the limitations of the existing analytical models. The model is validated by comparing the results obtained with the existing models.

  20. Graphene mediated Stark shifting of quantum dot energy levels

    Science.gov (United States)

    Kinnischtzke, Laura; Goodfellow, Kenneth M.; Chakraborty, Chitraleema; Lai, Yi-Ming; Fält, Stefan; Wegscheider, Werner; Badolato, Antonio; Vamivakas, A. Nick

    2016-05-01

    We demonstrate an optoelectronic device comprised of single InAs quantum dots in an n-i-Schottky diode where graphene has been used as the Schottky contact. Deterministic electric field tuning is shown using Stark-shifted micro-photoluminescence from single quantum dots. The extracted dipole moments from the Stark shifts are comparable to conventional devices where the Schottky contact is a semi-transparent metal. Neutral and singly charged excitons are also observed in the well-known Coulomb-blockade plateaus. Our results indicate that graphene is a suitable replacement for metal contacts in quantum dot devices which require electric field control.