scholarly journals Selfcomplementary Quantum Channels

2016 ◽  
Vol 23 (03) ◽  
pp. 1650014 ◽  
Author(s):  
Marek Smaczyński ◽  
Wojciech Roga ◽  
Karol Życzkowski
Keyword(s):  
Quantum System ◽  
Large Class ◽  
Time Evolution ◽  
Quantum State ◽  
Quantum Channels ◽  
Unknown Quantum State ◽  
Interacting Systems

Selfcomplementary quantum channels are characterized by such an interaction between the principal quantum system and the environment that leads to the same output states of both interacting systems. These maps can describe approximate quantum copy machines, as perfect copying of an unknown quantum state is not possible due to the celebrated no-cloning theorem. We provide here a parametrization of a large class of selfcomplementary channels and analyze their properties. Selfcomplementary channels preserve some residual coherences and residual entanglement. Investigating some measures of non-Markovianity, we show that time evolution under selfcomplementary channels is highly non-Markovian.

A time-dependent model for teleportation of a quantum state of position and momentum

2005 ◽  
Vol 83 (7) ◽  
pp. 687-698
Author(s):  
F M Toyama ◽  
K Saito
Keyword(s):  
Time Evolution ◽  
Quantum State ◽  
Quantum Teleportation ◽  
Time Dependent ◽  
Input State ◽  
Special Situation ◽  
Unknown Quantum State ◽  
Dependent Model ◽  
High Degree ◽  
Time Dependent Model

We present a time-dependent model for teleportation of an unknown quantum state of position and momentum. With this model, we analyze a situation in which Bob (receiver) is ignorant of the Hamiltonian that describes the time-evolution of a post-measurement state generated at Bob's site. We illustrate that the time-evolution of the post-measurement state deteriorates the fidelity of the quantum teleportation. We also illustrate a special situation in which a two-mode input state is transformed into a one-mode state by the teleportation. In addition, we discuss an optimal situation in which a high teleportation probability and a high degree of teleportation fidelity can be achieved.PACS Nos.: 03.65.–w, 03.67.Hk

scholarly journals Jordan products of quantum channels and their compatibility

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Mark Girard ◽  
Martin Plávala ◽  
Jamie Sikora
Keyword(s):  
Quantum State ◽  
Sufficient Conditions ◽  
The Other ◽  
Independent Interest ◽  
Quantum Channels ◽  
Semidefinite Programs ◽  
Jordan Product ◽  
Marginal Problem ◽  
Jordan Products ◽  
Product Of Matrices

AbstractGiven two quantum channels, we examine the task of determining whether they are compatible—meaning that one can perform both channels simultaneously but, in the future, choose exactly one channel whose output is desired (while forfeiting the output of the other channel). Here, we present several results concerning this task. First, we show it is equivalent to the quantum state marginal problem, i.e., every quantum state marginal problem can be recast as the compatibility of two channels, and vice versa. Second, we show that compatible measure-and-prepare channels (i.e., entanglement-breaking channels) do not necessarily have a measure-and-prepare compatibilizing channel. Third, we extend the notion of the Jordan product of matrices to quantum channels and present sufficient conditions for channel compatibility. These Jordan products and their generalizations might be of independent interest. Last, we formulate the different notions of compatibility as semidefinite programs and numerically test when families of partially dephasing-depolarizing channels are compatible.

Relative tomography of an unknown quantum state

2009 ◽  
Vol 79 (2) ◽  
Author(s):  
D. Mogilevtsev ◽  
J. Řeháček ◽  
Z. Hradil
Keyword(s):  
Quantum State ◽  
Unknown Quantum State

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.

scholarly journals Reading a Qubit Quantum State with a Quantum Meter: Time Unfolding of Quantum Darwinism and Quantum Information Flux

2019 ◽  
Vol 26 (04) ◽  
pp. 1950023
Author(s):  
Salvatore Lorenzo ◽  
Mauro Paternostro ◽  
G. Massimo Palma
Keyword(s):  
Quantum Information ◽  
Harmonic Oscillator ◽  
Quantum System ◽  
Quantum State ◽  
Common Theme ◽  
Quantum Harmonic Oscillator ◽  
Collision Model ◽  
Single Qubit ◽  
Quantum Darwinism

Quantum non-Markovianity and quantum Darwinism are two phenomena linked by a common theme: the flux of quantum information between a quantum system and the quantum environment it interacts with. In this work, making use of a quantum collision model, a formalism initiated by Sudarshan and his school, we will analyse the efficiency with which the information about a single qubit gained by a quantum harmonic oscillator, acting as a meter, is transferred to a bosonic environment. We will show how, in some regimes, such quantum information flux is inefficient, leading to the simultaneous emergence of non-Markovian and non-darwinistic behaviours.

scholarly journals Deterministic quantum teleportation through fiber channels

2018 ◽  
Vol 4 (10) ◽  
pp. eaas9401 ◽  
Author(s):  
Meiru Huo ◽  
Jiliang Qin ◽  
Jialin Cheng ◽  
Zhihui Yan ◽  
Zhongzhong Qin ◽  
...  
Keyword(s):  
Communication Networks ◽  
Quantum State ◽  
Optical Fibers ◽  
Quantum Teleportation ◽  
Continuous Variable ◽  
Entangled State ◽  
Optical Modes ◽  
Unknown Quantum State ◽  
Einstein Podolsky Rosen ◽  
Fiber Channels

Quantum teleportation, which is the transfer of an unknown quantum state from one station to another over a certain distance with the help of nonlocal entanglement shared by a sender and a receiver, has been widely used as a fundamental element in quantum communication and quantum computation. Optical fibers are crucial information channels, but teleportation of continuous variable optical modes through fibers has not been realized so far. Here, we experimentally demonstrate deterministic quantum teleportation of an optical coherent state through fiber channels. Two sub-modes of an Einstein-Podolsky-Rosen entangled state are distributed to a sender and a receiver through a 3.0-km fiber, which acts as a quantum resource. The deterministic teleportation of optical modes over a fiber channel of 6.0 km is realized. A fidelity of 0.62 ± 0.03 is achieved for the retrieved quantum state, which breaks through the classical limit of1/2. Our work provides a feasible scheme to implement deterministic quantum teleportation in communication networks.

Proposal for dimensionality testing in QPQ

2018 ◽  
Vol 18 (13&14) ◽  
pp. 1125-1142
Author(s):  
Arpita Maitra ◽  
Bibhas Adhikari ◽  
Satyabrata Adhikari
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Quantum System ◽  
Quantum State ◽  
Quantum Information Processing ◽  
Quantum States ◽  
Quantum Private Query ◽  
Unfair Advantage ◽  
Security Proofs

Recently, dimensionality testing of a quantum state has received extensive attention (Ac{\'i}n et al. Phys. Rev. Letts. 2006, Scarani et al. Phys. Rev. Letts. 2006). Security proofs of existing quantum information processing protocols rely on the assumption about the dimension of quantum states in which logical bits are encoded. However, removing such assumption may cause security loophole. In the present paper, we show that this is indeed the case. We choose two players' quantum private query protocol by Yang et al. (Quant. Inf. Process. 2014) as an example and show how one player can gain an unfair advantage by changing the dimension of subsystem of a shared quantum system. To resist such attack we propose dimensionality testing in a different way. Our proposal is based on CHSH like game. As we exploit CHSH like game, it can be used to test if the states are product states for which the protocol becomes completely vulnerable.

scholarly journals Twenty Years of Quantum State Teleportation at the Sapienza University in Rome

Entropy ◽  
2019 ◽  
Vol 21 (8) ◽  
pp. 768 ◽  
Author(s):  
Francesco De De Martini ◽  
Fabio Sciarrino
Keyword(s):  
Quantum Mechanics ◽  
Quantum Optics ◽  
Quantum State ◽  
Quantum Teleportation ◽  
Feed Forward ◽  
Unknown Quantum State ◽  
University Of Rome ◽  
The University ◽  
First Time

Quantum teleportation is one of the most striking consequence of quantum mechanics and is defined as the transmission and reconstruction of an unknown quantum state over arbitrary distances. This concept was introduced for the first time in 1993 by Charles Bennett and coworkers, it has then been experimentally demonstrated by several groups under different conditions of distance, amount of particles and even with feed forward. After 20 years from its first realization, this contribution reviews the experimental implementations realized at the Quantum Optics Group of the University of Rome La Sapienza.

Sign in / Sign up

Export Citation Format

Share Document