scholarly journals Double Slit with an Einstein–Podolsky–Rosen Pair

2020 ◽  
Vol 10 (3) ◽  
pp. 792 ◽  
Author(s):  
Bar Y. Peled ◽  
Amit Te’eni ◽  
Danko Georgiev ◽  
Eliahu Cohen ◽  
Avishy Carmi
Keyword(s):  
Continuous Variable ◽  
Quantum Systems ◽  
Quantum Measurements ◽  
Weak Measurements ◽  
Gaussian States ◽  
Bipartite Quantum Systems ◽  
Einstein Podolsky Rosen ◽  
Local Interference ◽  
Double Slit

In this somewhat pedagogical paper we revisit complementarity relations in bipartite quantum systems. Focusing on continuous-variable systems, we examine the influential class of EPR-like states through a generalization to Gaussian states and present some new quantitative relations between entanglement and local interference within symmetric and asymmetric double-double-slit scenarios. This approach is then related to ancilla-based quantum measurements, and weak measurements in particular. Finally, we tie up the notions of distinguishability, predictability, coherence and visibility while drawing some specific connections between them.

scholarly journals ENTANGLEMENT SHARING: FROM QUBITS TO GAUSSIAN STATES

2006 ◽  
Vol 04 (03) ◽  
pp. 383-393 ◽  
Author(s):  
GERARDO ADESSO ◽  
FABRIZIO ILLUMINATI
Keyword(s):  
Information Theory ◽  
Quantum Information ◽  
Quantum Correlations ◽  
Quantum Information Theory ◽  
Continuous Variable ◽  
Quantum Systems ◽  
Tripartite Entanglement ◽  
Gaussian States ◽  
Trade Off ◽  
Entanglement Sharing

It is a central trait of quantum information theory that there exist limitations to the free sharing of quantum correlations among multiple parties. Such monogamy constraints have been introduced in a landmark paper by Coffman, Kundu and Wootters, who derived a quantitative inequality expressing a trade-off between the couplewise and the genuine tripartite entanglement for states of three qubits. Since then, a lot of efforts have been devoted to the investigation of distributed entanglement in multipartite quantum systems. In this paper we report, in a unifying framework, a bird's eye view of the most relevant results that have been established so far on entanglement sharing in quantum systems. We will take off from the domain of N qubits, graze qudits, and finally land in the almost unexplored territory of multimode Gaussian states of continuous variable systems.

scholarly journals Gaussian states of continuous-variable quantum systems provide universal and versatile reservoir computing

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Johannes Nokkala ◽  
Rodrigo Martínez-Peña ◽  
Gian Luca Giorgi ◽  
Valentina Parigi ◽  
Miguel C. Soriano ◽  
...  
Keyword(s):  
Thermal Fluctuations ◽  
Continuous Variable ◽  
Quantum Systems ◽  
Full Potential ◽  
Reservoir Computing ◽  
Linear Dynamical Systems ◽  
Gaussian States ◽  
Proposed Model ◽  
Training Cost ◽  
The Rich

AbstractQuantum reservoir computing aims at harnessing the rich dynamics of quantum systems for machine-learning purposes. It can be used for online time series processing while having a remarkably low training cost. Here, we establish the potential of continuous-variable Gaussian states of linear dynamical systems for quantum reservoir computing. We prove that Gaussian resources are enough for universal reservoir computing. We find that encoding the input into Gaussian states is both a source and a means to tune the nonlinearity of the overall input-output map. We further show that the full potential of the proposed model can be reached by encoding to quantum fluctuations, such as squeezed vacuum, instead of classical fields or thermal fluctuations. Our results introduce a research paradigm for reservoir computing harnessing quantum systems and engineered Gaussian quantum states.

SPIN DISTRIBUTIONS FOR BIPARTITE QUANTUM SYSTEMS

2002 ◽  
Vol 17 (17) ◽  
pp. 2267-2281 ◽  
Author(s):  
A. R. USHA DEVI
Keyword(s):  
Comparative Study ◽  
Classical Limit ◽  
Singlet State ◽  
Quantum Systems ◽  
Quantum Spin ◽  
Spin Correlations ◽  
Bipartite Quantum Systems ◽  
Einstein Podolsky Rosen ◽  
Delta Functions ◽  
Spin Distributions

We carryout a comparative study of spin distributions defined over the sphere for bipartite quantum spin assemblies. We analyze Einstein–Podolsky–Rosen–Bohm (EPRB) spin correlations in a spin-s singlet state using these distributions. We observe that in the classical limit of s → ∞, EPRB spin distributions turn out to be delta functions, thus reflecting the perfect anticorrelation property of two-spin vectors associated with a spin-s singlet state.

scholarly journals Quantum Euler Relation for Local Measurements

Entropy ◽  
2021 ◽  
Vol 23 (7) ◽  
pp. 889
Author(s):  
Akram Touil ◽  
Kevin Weber ◽  
Sebastian Deffner
Keyword(s):  
Quantum Systems ◽  
Quantum Measurements ◽  
Weak Coupling Regime ◽  
Local Quantum ◽  
Dissipation Model ◽  
Local Measurements ◽  
Euler Relation ◽  
Quantum Analog ◽  
Back Action ◽  
Classical Thermodynamics

In classical thermodynamics the Euler relation is an expression for the internal energy as a sum of the products of canonical pairs of extensive and intensive variables. For quantum systems the situation is more intricate, since one has to account for the effects of the measurement back action. To this end, we derive a quantum analog of the Euler relation, which is governed by the information retrieved by local quantum measurements. The validity of the relation is demonstrated for the collective dissipation model, where we find that thermodynamic behavior is exhibited in the weak-coupling regime.

scholarly journals Timelessness Strictly Inside the Quantum Realm

Entropy ◽  
2021 ◽  
Vol 23 (6) ◽  
pp. 772
Author(s):  
Knud Thomsen
Keyword(s):  
Real World ◽  
Quantum Physics ◽  
Quantum Systems ◽  
The Real ◽  
Classical World ◽  
Quantum Objects ◽  
The Everyday ◽  
Double Slit

Time is one of the undisputed foundations of our life in the real world. Here it is argued that inside small isolated quantum systems, time does not pass as we are used to, and it is primarily in this sense that quantum objects enjoy only limited reality. Quantum systems, which we know, are embedded in the everyday classical world. Their preparation as well as their measurement-phases leave durable records and traces in the entropy of the environment. The Landauer Principle then gives a quantitative threshold for irreversibility. With double slit experiments and tunneling as paradigmatic examples, it is proposed that a label of timelessness offers clues for rendering a Copenhagen-type interpretation of quantum physics more “realistic” and acceptable by providing a coarse but viable link from the fundamental quantum realm to the classical world which humans directly experience.

scholarly journals Generation of Continuous Variable Einstein-Podolsky-Rosen Entanglement via the Kerr Nonlinearity in an Optical Fiber

2001 ◽  
Vol 86 (19) ◽  
pp. 4267-4270 ◽  
Author(s):  
Ch. Silberhorn ◽  
P. K. Lam ◽  
O. Weiß ◽  
F. König ◽  
N. Korolkova ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Kerr Nonlinearity ◽  
Continuous Variable ◽  
Einstein Podolsky Rosen

A matrix realignment method for recognizing entanglement

2003 ◽  
Vol 3 (3) ◽  
pp. 193-202
Author(s):  
K. Chen ◽  
L.-A. Wu
Keyword(s):  
Kronecker Product ◽  
Singular Values ◽  
Quantum Systems ◽  
Entangled States ◽  
Approximation Technique ◽  
Separable State ◽  
Simple Method ◽  
Bipartite Quantum Systems ◽  
The Matrix ◽  
Degree Of Entanglement

Motivated by the Kronecker product approximation technique, we have developed a very simple method to assess the inseparability of bipartite quantum systems, which is based on a realigned matrix constructed from the density matrix. For any separable state, the sum of the singular values of the matrix should be less than or equal to $1$. This condition provides a very simple, computable necessary criterion for separability, and shows powerful ability to identify most bound entangled states discussed in the literature. As a byproduct of the criterion, we give an estimate for the degree of entanglement of the quantum state.

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.

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