Entanglement entropy and determination of an unknown quantum state

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.

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Deterministic quantum teleportation through fiber channels

Science Advances ◽

10.1126/sciadv.aas9401 ◽

2018 ◽

Vol 4 (10) ◽

pp. eaas9401 ◽

Cited By ~ 21

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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Reconstructing a quantum state with a variational autoencoder

International Journal of Quantum Information ◽

10.1142/s0219749921400050 ◽

2021 ◽

Author(s):

Chuangtao Chen ◽

Zhimin He ◽

Zhiming Huang ◽

Haozhen Situ

Keyword(s):

Quantum State ◽

Circuit Simulation ◽

Entanglement Entropy ◽

Ghz State ◽

High Fidelity ◽

Training Samples ◽

Variational Autoencoder ◽

Minimum Number ◽

Number Formula ◽

State Tomography

Quantum state tomography (QST) is an important and challenging task in the field of quantum information, which has attracted a lot of attentions in recent years. Machine learning models can provide a classical representation of the quantum state after trained on the measurement outcomes, which are part of effective techniques to solve QST problem. In this work, we use a variational autoencoder (VAE) to learn the measurement distribution of two quantum states generated by MPS circuits. We first consider the Greenberger–Horne–Zeilinger (GHZ) state which can be generated by a simple MPS circuit. Simulation results show that a VAE can reconstruct 3- to 8-qubit GHZ states with a high fidelity, i.e., 0.99, and is robust to depolarizing noise. The minimum number ([Formula: see text]) of training samples required to reconstruct the GHZ state up to 0.99 fidelity scales approximately linearly with the number of qubits ([Formula: see text]). However, for the quantum state generated by a complex MPS circuit, [Formula: see text] increases exponentially with [Formula: see text], especially for the quantum state with high entanglement entropy.

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

Entropy ◽

10.3390/e21080768 ◽

2019 ◽

Vol 21 (8) ◽

pp. 768 ◽

Cited By ~ 1

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.

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Knotted Picture of Unknown Quantum State in Process of Quantum Teleportation

Communications in Theoretical Physics ◽

10.1088/0253-6102/49/5/16 ◽

2008 ◽

Vol 49 (5) ◽

pp. 1163-1164 ◽

Cited By ~ 6

Author(s):

Gu Zhi-Yu ◽

Qian Shang-Wu

Keyword(s):

Quantum State ◽

Quantum Teleportation ◽

Unknown Quantum State

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Stimulated Processes in a Half-collision

Laser Chemistry ◽

10.1155/lc.5.393 ◽

1986 ◽

Vol 5 (6) ◽

pp. 393-406

Author(s):

H. H. Telle

Keyword(s):

Kinetic Energy ◽

Quantum State ◽

Ground State ◽

Diatomic Molecules ◽

Dye Laser ◽

Interatomic Potentials ◽

Repulsive Potential ◽

Induced Absorption ◽

Tunable Dye Laser

Selective photodissociation of diatomic molecules is used to prepare the separating species in a well defined quantum state with narrowly determined final kinetic energy of the particles. During the course of separation to products the repulsive potential is probed by a tunable dye laser, that is by induced absorption in case the dissociation proceeds on a potential leading to ground state products, or by induced emission or absorption for all other cases. The determination of interatomic potentials from the observed spectra is discussed.

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