Construction of a qudit using Schrödinger cat states and generation of hybrid entanglement between a discrete-variable qudit and a continuous-variable qudit

2021 ◽  
Vol 104 (3) ◽  
Author(s):  
Qi-Ping Su ◽  
Tong Liu ◽  
Yu Zhang ◽  
Chui-Ping Yang
Keyword(s):  
Continuous Variable ◽  
Discrete Variable ◽  
Schrödinger Cat ◽  
Cat States

ENTANGLEMENT SWAPPING OF PAIR CAT STATES

2011 ◽  
Vol 09 (03) ◽  
pp. 993-1003
Author(s):  
YE-QI ZHANG ◽  
JING-BO XU
Keyword(s):  
Quantum Channel ◽  
Quantum Teleportation ◽  
Continuous Variable ◽  
Entanglement Swapping ◽  
Final States ◽  
Average Fidelity ◽  
Logarithmic Negativity ◽  
Squeezed Vacuum ◽  
Schrödinger Cat ◽  
Cat States

We investigate the entanglement swapping of the continuous variable states by taking the pair Schrödinger cat states as the input entangled states, in which the two-mode squeezed vacuum and the pair cat states serve as the quantum channel, respectively. The entanglement of the initial states as well as the final states is analyzed by adopting the logarithmic negativity as the measure of entanglement. The quantum teleportation task by exploiting the swapped states as the quantum channel is also considered, where a coherent state serves as the target state and the average fidelity is examined.

Generation of optical Schrödinger cat states in intense laser–matter interactions

2021 ◽  
Vol 17 (10) ◽  
pp. 1104-1108 ◽  
Author(s):  
M. Lewenstein ◽  
M. F. Ciappina ◽  
E. Pisanty ◽  
J. Rivera-Dean ◽  
P. Stammer ◽  
...  
Keyword(s):  
Intense Laser ◽  
Schrödinger Cat ◽  
Cat States

scholarly journals Quantum repeaters based on concatenated bosonic and discrete-variable quantum codes

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Filip Rozpędek ◽  
Kyungjoo Noh ◽  
Qian Xu ◽  
Saikat Guha ◽  
Liang Jiang
Keyword(s):  
Continuous Variable ◽  
Quantum Codes ◽  
Discrete Variable ◽  
Long Distance ◽  
Concatenated Code ◽  
Different Types ◽  
Optical Modes ◽  
Distance Communication ◽  
Quantum Repeaters ◽  
Quantum Error

AbstractWe propose an architecture of quantum-error-correction-based quantum repeaters that combines techniques used in discrete- and continuous-variable quantum information. Specifically, we propose to encode the transmitted qubits in a concatenated code consisting of two levels. On the first level we use a continuous-variable GKP code encoding the qubit in a single bosonic mode. On the second level we use a small discrete-variable code. Such an architecture has two important features. Firstly, errors on each of the two levels are corrected in repeaters of two different types. This enables for achieving performance needed in practical scenarios with a reduced cost with respect to an architecture for which all repeaters are the same. Secondly, the use of continuous-variable GKP code on the lower level generates additional analog information which enhances the error-correcting capabilities of the second-level code such that long-distance communication becomes possible with encodings consisting of only four or seven optical modes.

scholarly journals Phase-space studies of backscattering diffraction of defective Schrödinger cat states

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Damian Kołaczek ◽  
Bartłomiej J. Spisak ◽  
Maciej Wołoszyn
Keyword(s):  
Phase Space ◽  
Dispersive Medium ◽  
Wigner Distribution ◽  
Interference Term ◽  
Wigner Distribution Function ◽  
The Subject ◽  
Schrödinger Cat ◽  
Cat States ◽  
Schrodinger Cat State ◽  
Space Approach

AbstractThe coherent superposition of two well separated Gaussian wavepackets, with defects caused by their imperfect preparation, is considered within the phase-space approach based on the Wigner distribution function. This generic state is called the defective Schrödinger cat state due to this imperfection which significantly modifies the interference term. Propagation of this state in the phase space is described by the Moyal equation which is solved for the case of a dispersive medium with a Gaussian barrier in the above-barrier reflection regime. Formally, this regime constitutes conditions for backscattering diffraction phenomena. Dynamical quantumness and the degree of localization in the phase space of the considered state as a function of its imperfection are the subject of the performed analysis. The obtained results allow concluding that backscattering communication based on the defective Schrödinger cat states appears to be feasible with existing experimental capabilities.

scholarly journals QUANTUM FEEDBACK FOR PROTECTION OF SCHRÖDINGER CAT STATES

2000 ◽  
Author(s):  
M. FORTUNATO ◽  
P. TOMBESI ◽  
D. VITALI ◽  
J. M. RAIMOND
Keyword(s):  
Quantum Feedback ◽  
Schrödinger Cat ◽  
Cat States

scholarly journals On-chip continuous-variable quantum entanglement

Nanophotonics ◽  
2016 ◽  
Vol 5 (3) ◽  
pp. 469-482 ◽  
Author(s):  
Genta Masada ◽  
Akira Furusawa
Keyword(s):  
Quantum Information ◽  
Integrated Circuits ◽  
Quantum Entanglement ◽  
Information Science ◽  
Essential Feature ◽  
Continuous Variable ◽  
Entangled State ◽  
Discrete Variable ◽  
Light Beams ◽  
Optical Circuits

AbstractEntanglement is an essential feature of quantum theory and the core of the majority of quantum information science and technologies. Quantum computing is one of the most important fruits of quantum entanglement and requires not only a bipartite entangled state but also more complicated multipartite entanglement. In previous experimental works to demonstrate various entanglement-based quantum information processing, light has been extensively used. Experiments utilizing such a complicated state need highly complex optical circuits to propagate optical beams and a high level of spatial interference between different light beams to generate quantum entanglement or to efficiently perform balanced homodyne measurement. Current experiments have been performed in conventional free-space optics with large numbers of optical components and a relatively large-sized optical setup. Therefore, they are limited in stability and scalability. Integrated photonics offer new tools and additional capabilities for manipulating light in quantum information technology. Owing to integrated waveguide circuits, it is possible to stabilize and miniaturize complex optical circuits and achieve high interference of light beams. The integrated circuits have been firstly developed for discrete-variable systems and then applied to continuous-variable systems. In this article, we review the currently developed scheme for generation and verification of continuous-variable quantum entanglement such as Einstein-Podolsky-Rosen beams using a photonic chip where waveguide circuits are integrated. This includes balanced homodyne measurement of a squeezed state of light. As a simple example, we also review an experiment for generating discrete-variable quantum entanglement using integrated waveguide circuits.

scholarly journals Testing Quantum Coherence in Stochastic Electrodynamics with Squeezed Schrödinger Cat States

Atoms ◽  
2019 ◽  
Vol 7 (2) ◽  
pp. 42 ◽  
Author(s):  
Wayne Huang ◽  
Herman Batelaan
Keyword(s):  
Quantum Mechanics ◽  
Probability Distribution ◽  
Interference Pattern ◽  
Quantum Coherence ◽  
Laser Pulses ◽  
Quantum Probability ◽  
Harmonic Oscillators ◽  
Stochastic Electrodynamics ◽  
Schrödinger Cat ◽  
Cat States

The interference pattern in electron double-slit diffraction is a hallmark of quantum mechanics. A long-standing question for stochastic electrodynamics (SED) is whether or not it is capable of reproducing such effects, as interference is a manifestation of quantum coherence. In this study, we used excited harmonic oscillators to directly test this quantum feature in SED. We used two counter-propagating dichromatic laser pulses to promote a ground-state harmonic oscillator to a squeezed Schrödinger cat state. Upon recombination of the two well-separated wavepackets, an interference pattern emerges in the quantum probability distribution but is absent in the SED probability distribution. We thus give a counterexample that rejects SED as a valid alternative to quantum mechanics.

SUPERPOSITION OF THE λ-PARAMETERIZED SQUEEZED STATES

2000 ◽  
Vol 14 (07n08) ◽  
pp. 243-250
Author(s):  
XIAO-GUANG WANG ◽  
HONGCHEN FU
Keyword(s):  
Algebraic Characterization ◽  
Squeezed States ◽  
Nonclassical Properties ◽  
Intermediate States ◽  
Schrödinger Cat ◽  
Cat States ◽  
Superposition States

The superposition states of the λ-parameterized squeezed states are introduced and investigated. These states are intermediate states interpolating between the number and Schrödinger cat states and admit algebraic characterization in terms of su(1, 1) algebra. It is shown that these states exhibit remarkable nonclassical properties.

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