Self testing quantum apparatus

2004 ◽  
Vol 4 (4) ◽  
pp. 273-286
Author(s):  
D. Mayers ◽  
A. Yao
Keyword(s):  
Quantum Information ◽  
Quantum Cryptography ◽  
Quantum State ◽  
Quantum Communication ◽  
Probability Distributions ◽  
Bell State ◽  
The Self ◽  
Local Change ◽  
Measurement Apparatus ◽  
Orthogonal Measurement

We study, in the context of quantum information and quantum communication, a configuration of devices that includes (1) a source of some unknown bipartite quantum state that is claimed to be the Bell state $\Phi^+$ and (2) two spatially separated but otherwise unknown measurement apparatus, one on each side, that are each claimed to execute an orthogonal measurement at an angle $\theta \in \{-\pi/8, 0, \pi/8\}$ that is chosen by the user. We show that, if the nine distinct probability distributions that are generated by the self checking configuration, one for each pair of angles, are consistent with the specifications, the source and the two measurement apparatus are guaranteed to be identical to the claimed specifications up to a local change of basis on each side. We discuss the connection with quantum cryptography. testing quantum apparatus (pp273-286) D. Mayers and A. Yao We study, in the context of quantum information and quantum communication, a configuration of devices that includes (1) a source of some unknown bipartite quantum state that is claimed to be the Bell state $\Phi^+$ and (2) two spatially separated but otherwise unknown measurement apparatus, one on each side, that are each claimed to execute an orthogonal measurement at an angle $\theta \in \{-\pi/8, 0, \pi/8\}$ that is chosen by the user. We show that, if the nine distinct probability distributions that are generated by the self checking configuration, one for each pair of angles, are consistent with the specifications, the source and the two measurement apparatus are guaranteed to be identical to the claimed specifications up to a local change of basis on each side. We discuss the connection with quantum cryptography.

On the classical character of control fields in quantum information processing

2002 ◽  
Vol 2 (1) ◽  
pp. 1-13
Author(s):  
S.J. van Enk ◽  
H.J. Kimble
Keyword(s):  
Quantum Computing ◽  
Information Processing ◽  
Quantum Information ◽  
Laser Beam ◽  
Quantum State ◽  
Quantum Communication ◽  
Quantum Information Processing ◽  
Laser Fields ◽  
Undesirable Property

Control fields in quantum information processing are almost by definition assumed to be classical. In reality, however, when such a field is used to manipulate the quantum state of qubits, the qubits always become slightly entangled with the field. For quantum information processing this is an undesirable property, as it precludes perfect quantum computing and quantum communication. Here we consider the interaction of atomic qubits with laser fields and quantify atom-field entanglement in various cases of interest. We find that the entanglement decreases with the average number of photons \bar{n} in a laser beam as $E\propto\log_2 \bar{n}/\bar{n}$ for $\bar{n}\rightarrow\infty$.

scholarly journals From Stochastic Optics to theWigner Formalism: The Role of the Vacuum Field in Optical Quantum Communication Experiments

Atoms ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 76 ◽  
Author(s):  
Alberto Casado ◽  
Santiago Guerra ◽  
José Plácido
Keyword(s):  
Quantum Cryptography ◽  
Physical Meaning ◽  
Quantum Communication ◽  
Bell State ◽  
Vacuum Field ◽  
Heisenberg Picture ◽  
Parametric Down Conversion ◽  
The Relationship ◽  
Down Conversion

TheWigner formalism in the Heisenberg picture constitutes a bridge that connects QuantumOptics to Stochastic Optics. The vacuum field appears explicitly in the formalism, and the wavelikeaspects of light are emphasised. In addition, the zeropoint intensity as a threshold for detection is acommon denominator in both theories. In this paper, after summarising the basic rules of the Wignerapproach and its application to parametric down-conversion, some new results are presented thatdelve into the physical meaning of the zeropoint field in optical quantum communication. Specifically,the relationship between Bell-state distinguishability and the number of sets of zeropoint modesthat take part in the experiment is analysed in terms of the coupling between the phases of thedifferent fields involved and the subtraction of the zeropoint intensity at the detectors. Additionally,the connection between the compatibility theorem in quantum cryptography and zeropoint fieldis stressed.

A GENERALIZED CONDITION FOR TELEPORTATION OF THE QUANTUM STATE OF AN ASSEMBLY OF N TWO-LEVEL SYSTEM

2007 ◽  
Vol 21 (29) ◽  
pp. 2019-2023 ◽  
Author(s):  
HARI PRAKASH ◽  
NARESH CHANDRA ◽  
RANJANA PRAKASH ◽  
AMBESH DIXIT
Keyword(s):  
Quantum Information ◽  
Quantum State ◽  
Unitary Transformation ◽  
Bell State ◽  
Entangled State ◽  
Level System ◽  
Bell State Measurement ◽  
Original State ◽  
State Measurement ◽  
Two Level Systems

We consider the teleportation of quantum information consisting of the quantum state of a set S1 of N two-level systems (TLSs), using EPR entangled state consisting of set S2⊕S3 where set S2 has M TLSs and set S3 has N TLSs. The Bell state measurement is done on set S1⊕S2 and a unitary transformation, dependent on this result, on the quantum state of set S3 generates a replica of the original state of set S1. We show rigorously that the teleportation is possible only if M ≥ N.

scholarly journals Quantum state transmission over partially corrupted quantum information network

2020 ◽  
Vol 2 (3) ◽  
Author(s):  
Masahito Hayashi ◽  
Seunghoan Song
Keyword(s):  
Quantum Information ◽  
Quantum State ◽  
Information Network ◽  
State Transmission

scholarly journals Multiparty weighted threshold quantum secret sharing based on the Chinese remainder theorem to share quantum information

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yao-Hsin Chou ◽  
Guo-Jyun Zeng ◽  
Xing-Yu Chen ◽  
Shu-Yu Kuo
Keyword(s):  
Quantum Information ◽  
Phase Shift ◽  
Quantum State ◽  
Secret Sharing ◽  
Chinese Remainder Theorem ◽  
Security Analysis ◽  
Quantum Secret Sharing ◽  
Security Protocol ◽  
Multiple Quantum ◽  
Cryptographic Primitive

AbstractSecret sharing is a widely-used security protocol and cryptographic primitive in which all people cooperate to restore encrypted information. The characteristics of a quantum field guarantee the security of information; therefore, many researchers are interested in quantum cryptography and quantum secret sharing (QSS) is an important research topic. However, most traditional QSS methods are complex and difficult to implement. In addition, most traditional QSS schemes share classical information, not quantum information which makes them inefficient to transfer and share information. In a weighted threshold QSS method, each participant has each own weight, but assigning weights usually costs multiple quantum states. Quantum state consumption will therefore increase with the weight. It is inefficient and difficult, and therefore not able to successfully build a suitable agreement. The proposed method is the first attempt to build multiparty weighted threshold QSS method using single quantum particles combine with the Chinese remainder theorem (CRT) and phase shift operation. The proposed scheme allows each participant has its own weight and the dealer can encode a quantum state with the phase shift operation. The dividing and recovery characteristics of CRT offer a simple approach to distribute partial keys. The reversibility of phase shift operation can encode and decode the secret. The proposed weighted threshold QSS scheme presents the security analysis of external attacks and internal attacks. Furthermore, the efficiency analysis shows that our method is more efficient, flexible, and simpler to implement than traditional methods.

scholarly journals Practical quantum teleportation of an unknown quantum state

2017 ◽  
Vol 95 (5) ◽  
pp. 498-503
Author(s):  
Syed Tahir Amin ◽  
Aeysha Khalique
Keyword(s):  
Quantum State ◽  
Quantum Teleportation ◽  
Bell State ◽  
Linear Optics ◽  
State Measurement ◽  
Dark Counts ◽  
Experimental Parameters ◽  
Unknown Quantum State ◽  
Down Conversion ◽  
Good Agreement

We present our model to teleport an unknown quantum state using entanglement between two distant parties. Our model takes into account experimental limitations due to contribution of multi-photon pair production of parametric down conversion source, inefficiency, dark counts of detectors, and channel losses. We use a linear optics setup for quantum teleportation of an unknown quantum state by the sender performing a Bell state measurement. Our theory successfully provides a model for experimentalists to optimize the fidelity by adjusting the experimental parameters. We apply our model to a recent experiment on quantum teleportation and the results obtained by our model are in good agreement with the experimental results.

EFFICIENT ALGORITHM FOR INITIALIZING AMPLITUDE DISTRIBUTION OF A QUANTUM REGISTER

2001 ◽  
Vol 15 (27) ◽  
pp. 1259-1264 ◽  
Author(s):  
M. ANDRECUT ◽  
M. K. ALI
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Quantum Computation ◽  
Quantum State ◽  
Efficient Algorithm ◽  
Quantum Information Processing ◽  
Amplitude Distribution ◽  
Quantum Register

The preparation of a quantum register in an arbitrary superposed quantum state is an important operation for quantum computation and quantum information processing. Here, we present an efficient algorithm which requires a polynomial number of elementary operations for initializing the amplitude distribution of a quantum register.

Sign in / Sign up

Export Citation Format

Share Document