EPR Pair and Measurement

2020 ◽  
pp. 37-63
Keyword(s):  
Epr Pair

Superdense Coding and Quantum Teleportation

2006 ◽  
Author(s):  
Phillip Kaye ◽  
Raymond Laflamme ◽  
Michele Mosca
Keyword(s):  
Quantum Teleportation ◽  
Communication Channel ◽  
Quantum Communication ◽  
Communication Protocols ◽  
Bell State ◽  
Third Party ◽  
Classical Communication ◽  
Superdense Coding ◽  
Communication Task ◽  
Epr Pair

We are now ready to look at our first protocols for quantum information. In this section, we examine two communication protocols which can be implemented using the tools we have developed in the preceding sections. These protocols are known as superdense coding and quantum teleportation. Both are inherently quantum: there are no classical protocols which behave in the same way. Both involve two parties who wish to perform some communication task between them. In descriptions of such communication protocols (especially in cryptography), it is very common to name the two parties ‘Alice’ and ‘Bob’, for convenience. We will follow this tradition. We will repeatedly refer to communication channels. A quantum communication channel refers to a communication line (e.g. a fiberoptic cable), which can carry qubits between two remote locations. A classical communication channel is one which can carry classical bits (but not qubits).1 The protocols (like many in quantum communication) require that Alice and Bob initially share an entangled pair of qubits in the Bell state The above Bell state is sometimes referred to as an EPR pair. Such a state would have to be created ahead of time, when the qubits are in a lab together and can be made to interact in a way which will give rise to the entanglement between them. After the state is created, Alice and Bob each take one of the two qubits away with them. Alternatively, a third party could create the EPR pair and give one particle to Alice and the other to Bob. If they are careful not to let them interact with the environment, or any other quantum system, Alice and Bob’s joint state will remain entangled. This entanglement becomes a resource which Alice and Bob can use to achieve protocols such as the following. Suppose Alice wishes to send Bob two classical bits of information. Superdense coding is a way of achieving this task over a quantum channel, requiring only that Alice send one qubit to Bob. Alice and Bob must initially share the Bell state Suppose Alice is in possession of the first qubit and Bob the second qubit.

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

2006 ◽  
Vol 23 (12) ◽  
pp. 3142-3144 ◽  
Author(s):  
Wang Ya-Hong ◽  
Yu Chang-Shui ◽  
Song He-Shan
Keyword(s):  
Epr Pair

QUANTUM SECURE DIRECT COMMUNICATION WITH A CONSTANT NUMBER OF EPR PAIRS

2010 ◽  
Vol 08 (08) ◽  
pp. 1355-1371 ◽  
Author(s):  
CHIN-YUNG LU ◽  
SHIOU-AN WANG ◽  
YUH-JIUH CHENG ◽  
SY-YEN KUO
Keyword(s):  
Quantum Secure Direct Communication ◽  
Secret Message ◽  
Constant Number ◽  
Dense Coding ◽  
Direct Communication ◽  
Epr Pairs ◽  
Single Qubit ◽  
Coding Scheme ◽  
Einstein Podolsky Rosen ◽  
Epr Pair

In this paper, we propose a quantum secure direct communication (QSDC) protocol based on Einstein–Podolsky–Rosen (EPR) pairs. Previous QSDC protocols usually consume one EPR pair to transmit a single qubit. If Alice wants to transmit an n-bit message, she needs at least n/2 EPR pairs when a dense coding scheme is used. In our protocol, if both Alice and Bob preshare 2c + 1 EPR pairs with the trusted server, where c is a constant, Alice can transmit an arbitrary number of qubits to Bob. The 2c EPR pairs are used by Alice and Bob to authenticate each other and the remaining EPR pair is used to encode and decode the message qubit. Thus the total number of EPR pairs used for one communication is a constant no matter how many bits will be transmitted. It is not necessary to transmit EPR pairs before transmitting the secret message except for the preshared constant number of EPR pairs. This reduces both the utilization of the quantum channel and the risk. In addition, after the authentication, the server is not involved in the message transmission. Thus we can prevent the server from knowing the message.

Controlled Teleportation of an Arbitrary Two-Particle State by One EPR Pair and Cluster State

2011 ◽  
Vol 56 (5) ◽  
pp. 819-823 ◽  
Author(s):  
Zhan-Ying Guo ◽  
Xiao-Xing Shang ◽  
Jian-Xing Fang ◽  
Rui-Hua Xiao
Keyword(s):  
Cluster State ◽  
Controlled Teleportation ◽  
Particle State ◽  
Epr Pair

TELEPORTATION OF ANY FORM OF SINGLE-MODE QUANTUM STATES

2006 ◽  
Vol 20 (02n03) ◽  
pp. 97-103
Author(s):  
TONG-QIANG SONG
Keyword(s):  
Quantum Channel ◽  
Quantum Teleportation ◽  
Single Mode ◽  
Continuous Variable ◽  
Quantum States ◽  
Squeezed Vacuum ◽  
Einstein Podolsky Rosen ◽  
Epr Pair

By using the two-mode Einstein–Podolsky–Rosen (EPR) pair eigenstates or the two-mode squeezed vacuum as quantum channel we study the quantum teleportation of any form of single-mode quantum states (which include discrete and continuous variable quantum states). The elegant properties of the EPR pair eigenstates bring much convenience to our discussion.

scholarly journals Einstein-Podolsky-Rosen correlation seen from moving observers

2003 ◽  
Vol 3 (3) ◽  
pp. 224-228
Author(s):  
H. Terashima ◽  
M. Ueda
Keyword(s):  
Quantum Theory ◽  
Quantum Communication ◽  
Relativistic Quantum ◽  
Entangled State ◽  
Local Correlation ◽  
Relativistic Quantum Theory ◽  
Gedanken Experiment ◽  
Einstein Podolsky Rosen ◽  
Non Local ◽  
Epr Pair

Within the framework of relativistic quantum theory, we consider the Einstein-Podolsky-Rosen (EPR) gedanken-experiment in which measurements of the spin are performed by moving observers. We find that the perfect anti-correlation in the same direction between the EPR pair no longer holds in the observers' frame. This does not imply a breakdown of the non-local correlation. We explicitly show that the observers must measure the spin in appropriately chosen different directions in order to observe the perfect anti-correlation. This fact should be taken into account in utilizing the entangled state in quantum communication by moving observers.

scholarly journals Time evolution of quantum entanglement of an EPR pair in a localized environment

2018 ◽  
Vol 20 (5) ◽  
pp. 053015 ◽  
Author(s):  
Jia Wang ◽  
Xia-Ji Liu ◽  
Hui Hu
Keyword(s):  
Time Evolution ◽  
Quantum Entanglement ◽  
Epr Pair
Sign in / Sign up

Export Citation Format

Share Document