scholarly journals A Generalized Quantum Optical Scheme for Implementing Open Quantum Walks

2020 ◽  
Vol 315 ◽  
pp. 83-92
Author(s):  
Ayanda Romanis Zungu ◽  
IIya Sinayskiy ◽  
Francesco Petruccione
Keyword(s):  
Quantum Walks ◽  
Optical Scheme ◽  
Open Quantum ◽  
Quantum Optical

Quantum optical implementation of open quantum walks

2014 ◽  
Vol 12 (02) ◽  
pp. 1461010 ◽  
Author(s):  
Ilya Sinayskiy ◽  
Francesco Petruccione
Keyword(s):  
Cavity Mode ◽  
Quantum Walks ◽  
Optical Scheme ◽  
Fock States ◽  
Open Quantum ◽  
Effective Dynamics ◽  
Level Atom ◽  
Physical Implementation ◽  
Quantum Optical

A quantum optical implementation of the recently proposed open quantum walks (OQWs) is suggested. In the presented quantum optical scheme a two level atom plays the role of the "walker" and the Fock states of the cavity mode correspond to the lattice sites of the OQW. Using the small unitary rotations approach the effective dynamics of the system is shown to be an OQW. The presented scheme allows for a simple physical implementation of the OQW formalism, but it can be extended to create more diverse OQWs.

Higher-dimensional open quantum walk in environment of quantum Bernoulli noises

2021 ◽  
pp. 2250001
Author(s):  
Ce Wang
Keyword(s):  
Quantum Walk ◽  
Quantum Walks ◽  
Initial State ◽  
Quantum Random Walks ◽  
Open Quantum ◽  
Higher Dimensional ◽  
Gauss Type ◽  
Open Quantum Random Walks ◽  
Limit Probability ◽  
Creation Operators

Open quantum walks (OQWs) (also known as open quantum random walks) are quantum analogs of classical Markov chains in probability theory, and have potential application in quantum information and quantum computation. Quantum Bernoulli noises (QBNs) are annihilation and creation operators acting on Bernoulli functionals, and can be used as the environment of an open quantum system. In this paper, by using QBNs as the environment, we introduce an OQW on a general higher-dimensional integer lattice. We obtain a quantum channel representation of the walk, which shows that the walk is indeed an OQW. We prove that all the states of the walk are separable provided its initial state is separable. We also prove that, for some initial states, the walk has a limit probability distribution of higher-dimensional Gauss type. Finally, we show links between the walk and a unitary quantum walk recently introduced in terms of QBNs.

scholarly journals Semi-device-independent framework based on natural physical assumptions

Quantum ◽  
2017 ◽  
Vol 1 ◽  
pp. 33 ◽  
Author(s):  
Thomas Van Himbeeck ◽  
Erik Woodhead ◽  
Nicolas J. Cerf ◽  
Raúl García-Patrón ◽  
Stefano Pironio
Keyword(s):  
Fock Space ◽  
Outcome Measurement ◽  
Photon Number ◽  
Quantum Correlations ◽  
Mean Value ◽  
Laser Source ◽  
Optical Scheme ◽  
Infinite Dimensional ◽  
Energy Constrained ◽  
Quantum Optical

The semi-device-independent approach provides a framework for prepare-and-measure quantum protocols using devices whose behavior must not be characterized nor trusted, except for a single assumption on the dimension of the Hilbert space characterizing the quantum carriers. Here, we propose instead to constrain the quantum carriers through a bound on the mean value of a well-chosen observable. This modified assumption is physically better motivated than a dimension bound and closer to the description of actual experiments. In particular, we consider quantum optical schemes where the source emits quantum states described in an infinite-dimensional Fock space and model our assumption as an upper bound on the average photon number in the emitted states. We characterize the set of correlations that may be exhibited in the simplest possible scenario compatible with our new framework, based on two energy-constrained state preparations and a two-outcome measurement. Interestingly, we uncover the existence of quantum correlations exceeding the set of classical correlations that can be produced by devices behaving in a purely pre-determined fashion (possibly including shared randomness). This feature suggests immediate applications to certified randomness generation. Along this line, we analyze the achievable correlations in several prepare-and-measure optical schemes with a mean photon number constraint and demonstrate that they allow for the generation of certified randomness. Our simplest optical scheme works by the on-off keying of an attenuated laser source followed by photocounting. It opens the path to more sophisticated energy-constrained semi-device-independent quantum cryptography protocols, such as quantum key distribution.

scholarly journals Microscopic derivation of open quantum walks

2014 ◽  
Author(s):  
Ilya Sinayskiy ◽  
Francesco Petruccione
Keyword(s):  
Quantum Walks ◽  
Open Quantum ◽  
Microscopic Derivation

scholarly journals Generalized Open Quantum Walks on Apollonian Networks

PLoS ONE ◽  
2015 ◽  
Vol 10 (7) ◽  
pp. e0130967 ◽  
Author(s):  
Łukasz Pawela ◽  
Piotr Gawron ◽  
Jarosław Adam Miszczak ◽  
Przemysław Sadowski
Keyword(s):  
Quantum Walks ◽  
Open Quantum

scholarly journals Open quantum systems for quarkonia

2021 ◽  
pp. 2130010
Author(s):  
Xiaojun Yao
Keyword(s):  
Quantum System ◽  
Open Quantum System ◽  
Open Quantum Systems ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Effective Field ◽  
Quantum Brownian Motion ◽  
Open Quantum ◽  
Ion Collisions ◽  
Quantum Optical

I review recent applications of the open quantum system framework in the understanding of quarkonium suppression in heavy-ion collisions, which has been used as a probe of the quark–gluon plasma for decades. The derivation of the Lindblad equations for quarkonium in both the quantum Brownian motion and the quantum optical limits and their semiclassical counterparts is explained. The hierarchy of time scales assumed in the derivation is justified from the separation of energy scales in nonrelativistic effective field theories of QCD. Physical implications of the open quantum system approach are also discussed. Finally, I list some open questions for future studies.

scholarly journals Gaussian Quantum Trajectories for the Variational Simulation of Open Quantum-Optical Systems

2018 ◽  
Vol 8 (9) ◽  
pp. 1427 ◽  
Author(s):  
Wouter Verstraelen ◽  
Michiel Wouters
Keyword(s):  
Open Quantum Systems ◽  
Computational Cost ◽  
System Size ◽  
Quantum Systems ◽  
Optical Systems ◽  
Quantum Trajectory ◽  
Quantum Trajectories ◽  
Open Quantum ◽  
Quantum Optical ◽  
Bistability Regime

We construct a class of variational methods for the study of open quantum systems based on Gaussian ansatzes for the quantum trajectory formalism. Gaussianity in the conjugate position and momentum quadratures is distinguished from Gaussianity in density and phase. We apply these methods to a driven-dissipative Kerr cavity where we study dephasing and the stationary states throughout the bistability regime. Computational cost proves to be similar to the Truncated Wigner Approximation (TWA) method, with at most quadratic scaling in system size. Meanwhile, strong correspondence with the numerically-exact trajectory description is maintained so that these methods contain more information on the ensemble constitution than TWA and can be more robust.

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