scholarly journals Geometric measure of entanglement of multi-qubit graph states and its detection on a quantum computer

2021 ◽  
Author(s):  
Khrystyna Gnatenko ◽  
Nataliia A. Susulovska
Keyword(s):  
Phase Shift ◽  
Quantum State ◽  
Quantum Computer ◽  
Graph States ◽  
Geometric Measure ◽  
Shift Operators ◽  
Quantum Device ◽  
Geometric Measure Of Entanglement ◽  
Arbitrary Graphs ◽  
Good Agreement

Abstract Multi-qubit graph states generated by the action of controlled phase shift operators on a separable quantum state of a system, in which all the qubits are in arbitrary identical states, are examined. The geometric measure of entanglement of a qubit with other qubits is found for the graph states represented by arbitrary graphs. The entanglement depends on the degree of the vertex representing the qubit, the absolute values of the parameter of the phase shift gate and the parameter of state the gate is acting on. Also the geometric measure of entanglement of the graph states is quantified on the quantum computer ibmq athens. The results obtained on the quantum device are in good agreement with analytical ones.

scholarly journals Multiparty weighted threshold quantum secret sharing based on the Chinese remainder theorem to share quantum information

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yao-Hsin Chou ◽  
Guo-Jyun Zeng ◽  
Xing-Yu Chen ◽  
Shu-Yu Kuo
Keyword(s):  
Quantum Information ◽  
Phase Shift ◽  
Quantum State ◽  
Secret Sharing ◽  
Chinese Remainder Theorem ◽  
Security Analysis ◽  
Quantum Secret Sharing ◽  
Security Protocol ◽  
Multiple Quantum ◽  
Cryptographic Primitive

AbstractSecret sharing is a widely-used security protocol and cryptographic primitive in which all people cooperate to restore encrypted information. The characteristics of a quantum field guarantee the security of information; therefore, many researchers are interested in quantum cryptography and quantum secret sharing (QSS) is an important research topic. However, most traditional QSS methods are complex and difficult to implement. In addition, most traditional QSS schemes share classical information, not quantum information which makes them inefficient to transfer and share information. In a weighted threshold QSS method, each participant has each own weight, but assigning weights usually costs multiple quantum states. Quantum state consumption will therefore increase with the weight. It is inefficient and difficult, and therefore not able to successfully build a suitable agreement. The proposed method is the first attempt to build multiparty weighted threshold QSS method using single quantum particles combine with the Chinese remainder theorem (CRT) and phase shift operation. The proposed scheme allows each participant has its own weight and the dealer can encode a quantum state with the phase shift operation. The dividing and recovery characteristics of CRT offer a simple approach to distribute partial keys. The reversibility of phase shift operation can encode and decode the secret. The proposed weighted threshold QSS scheme presents the security analysis of external attacks and internal attacks. Furthermore, the efficiency analysis shows that our method is more efficient, flexible, and simpler to implement than traditional methods.

Quantum algorithm for measuring the energy of n qubits with unknown pair-interactions

2002 ◽  
Vol 2 (3) ◽  
pp. 198-207
Author(s):  
D. Janzing
Keyword(s):  
Quantum State ◽  
Quantum Computer ◽  
Quantum Algorithm ◽  
Pair Interaction ◽  
Phase Estimation ◽  
Solid States ◽  
Energy Gaps ◽  
Large N ◽  
Conditional Transformation ◽  
Essential Assumption

The well-known algorithm for quantum phase estimation requires that the considered unitary is available as a conditional transformation depending on the quantum state of an ancilla register. We present an algorithm converting an unknown n-qubit pair-interaction Hamiltonian into a conditional one such that standard phase estimation can be applied to measure the energy. Our essential assumption is that the considered system can be brought into interaction with a quantum computer. For large n the algorithm could still be applicable for estimating the density of energy states and might therefore be useful for finding energy gaps in solid states.

Phase shift of a rotated quantum state observed in an x-ray scattering experiment

1992 ◽  
Vol 69 (5) ◽  
pp. 699-702 ◽  
Author(s):  
D. E. Brown ◽  
J. Arthur ◽  
A. Q. R. Baron ◽  
G. S. Brown ◽  
S. Shastri
Keyword(s):  
Phase Shift ◽  
Quantum State ◽  
X Ray ◽  
X Ray Scattering ◽  
Scattering Experiment ◽  
Ray Scattering

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 Option Pricing using Quantum Computers

Quantum ◽  
2020 ◽  
Vol 4 ◽  
pp. 291 ◽  
Author(s):  
Nikitas Stamatopoulos ◽  
Daniel J. Egger ◽  
Yue Sun ◽  
Christa Zoufal ◽  
Raban Iten ◽  
...  
Keyword(s):  
Option Pricing ◽  
Quantum Computer ◽  
Quantum Circuits ◽  
Quantum Computers ◽  
Barrier Options ◽  
Error Mitigation ◽  
Quantum Device ◽  
Amplitude Estimation ◽  
Simulation Results ◽  
Path Dependent

We present a methodology to price options and portfolios of options on a gate-based quantum computer using amplitude estimation, an algorithm which provides a quadratic speedup compared to classical Monte Carlo methods. The options that we cover include vanilla options, multi-asset options and path-dependent options such as barrier options. We put an emphasis on the implementation of the quantum circuits required to build the input states and operators needed by amplitude estimation to price the different option types. Additionally, we show simulation results to highlight how the circuits that we implement price the different option contracts. Finally, we examine the performance of option pricing circuits on quantum hardware using the IBM Q Tokyo quantum device. We employ a simple, yet effective, error mitigation scheme that allows us to significantly reduce the errors arising from noisy two-qubit gates.

Fundamentals of Quantum Computing, Quantum Supremacy, and Quantum Machine Learning

2021 ◽  
pp. 21-46
Author(s):  
Kamaljit I. Lakhtaria ◽  
Vrunda Gadesha
Keyword(s):  
Machine Learning ◽  
Quantum Computing ◽  
Quantum Computer ◽  
Error Mitigation ◽  
Fundamental Goal ◽  
Quantum Device ◽  
Quantum Machine Learning ◽  
Simulation Error ◽  
The Difference ◽  
Quantum Optimization

When we aim to demonstrate that a programmable quantum device can solve complex problems which cannot be addressed by classic computers, this fundamental goal is known as quantum supremacy. This concept has changed every fundamental rule of computation. In this chapter, the detailed concept of quantum computing and quantum supremacy is explained along with various open source tools and real-time applications of this technology. The major base concepts, quantum computing, the difference between classical and quantum computer on physical level, programing quantum device, and the experiment-quantum supremacy are explained conceptually. This chapter also includes an introduction of the tools Cirq and OpenFermion plus the applications like quantum simulation, error mitigation technique, quantum machine learning, and quantum optimization, which are explained with illustrations.

scholarly journals Geometric measure of entanglement and shared quantum states

2008 ◽  
Vol 78 (3) ◽  
Author(s):  
Levon Tamaryan ◽  
DaeKil Park ◽  
Jin-Woo Son ◽  
Sayatnova Tamaryan
Keyword(s):  
Quantum States ◽  
Geometric Measure ◽  
Geometric Measure Of Entanglement
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