Arbitrary quantum superposition state for three-level system using oscillating dark states

2009 ◽  
Vol 282 (6) ◽  
pp. 1167-1170
Author(s):  
Jun He ◽  
Yong-Sheng Zhang ◽  
Xiang-Fa Zhou ◽  
Qun-Feng Chen ◽  
Guang-Can Guo
Keyword(s):  
Level System ◽  
Superposition State ◽  
Quantum Superposition ◽  
Arbitrary Quantum

scholarly journals Coherent electron displacement for quantum information processing using attosecond single cycle pulses

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Hicham Agueny
Keyword(s):  
Quantum Information ◽  
Quantum Information Processing ◽  
Coherent Motion ◽  
Superposition State ◽  
Phase Information ◽  
Quantum Superposition ◽  
Single Cycle ◽  
Precise Control ◽  
Advanced Control ◽  
A Chain

AbstractCoherent electron displacement is a conventional strategy for processing quantum information, as it enables to interconnect distinct sites in a network of atoms. The efficiency of the processing relies on the precise control of the mechanism, which has yet to be established. Here, we theoretically demonstrate a new route to drive the electron displacement on a timescale faster than that of the dynamical distortion of the electron wavepacket by utilizing attosecond single-cycle pulses. The characteristic feature of these pulses relies on a vast momentum transfer to an electron, leading to its displacement following a unidirectional path. The scenario is illustrated by revealing the spatiotemporal nature of the displaced wavepacket encoding a quantum superposition state. We map out the associated phase information and retrieve it over long distances from the origin. Moreover, we show that a sequence of such pulses applied to a chain of ions enables attosecond control of the directionality of the coherent motion of the electron wavepacket back and forth between the neighbouring sites. An extension to a two-electron spin state demonstrates the versatility of the use of these pulses. Our findings establish a promising route for advanced control of quantum states using attosecond single-cycle pulses, which pave the way towards ultrafast processing of quantum information as well as imaging.

scholarly journals Provably Quantum-Secure Tweakable Block Ciphers

2021 ◽  
pp. 337-377
Author(s):  
Akinori Hosoyamada ◽  
Tetsu Iwata
Keyword(s):  
Polynomial Time ◽  
Provable Security ◽  
Block Cipher ◽  
Block Ciphers ◽  
Quantum Superposition ◽  
Quantum Cryptanalysis ◽  
Classical Setting ◽  
Time Quantum ◽  
Symmetric Key ◽  
Arbitrary Quantum

Recent results on quantum cryptanalysis show that some symmetric key schemes can be broken in polynomial time even if they are proven to be secure in the classical setting. Liskov, Rivest, and Wagner showed that secure tweakable block ciphers can be constructed from secure block ciphers in the classical setting. However, Kaplan et al. showed that their scheme can be broken by polynomial time quantum superposition attacks, even if underlying block ciphers are quantum-secure. Since then, it remains open if there exists a mode of block ciphers to build quantum-secure tweakable block ciphers. This paper settles the problem in the reduction-based provable security paradigm. We show the first design of quantum-secure tweakable block ciphers based on quantum-secure block ciphers, and present a provable security bound. Our construction is simple, and when instantiated with a quantum-secure n-bit block cipher, it is secure against attacks that query arbitrary quantum superpositions of plaintexts and tweaks up to O(2n/6) quantum queries. Our security proofs use the compressed oracle technique introduced by Zhandry. More precisely, we use an alternative formalization of the technique introduced by Hosoyamada and Iwata.

scholarly journals Multiparticle Quantum Superposition and Stimulated Entanglement by Parity Selective Amplification of Entangled States

2001 ◽  
Vol 56 (1-2) ◽  
pp. 61-66 ◽  
Author(s):  
Francesco De Martini ◽  
Giovanni Di Giuseppe
Keyword(s):  
Superposition State ◽  
Quantum Superposition ◽  
Standard Quantum ◽  
Photon State ◽  
Two Photon ◽  
Pacs 03.65 ◽  
Basic Physics ◽  
Relevant Role ◽  
Free Environment ◽  
Nonlocal Structure

AbstractA multiparticle quantum superposition state has been generated by a novel phase-selective parametric amplifier of an entangled two-photon state. This realization is expected to open a new field of investigations on the persistence of the validity of the standard quantum theory for systems of increasing complexity, in a quasi decoherence-free environment. Because of its nonlocal structure the new system is expected to play a relevant role in the modem endeavor on quantum information and in the basic physics of entanglement. - Pacs: 03.65.Bz, 03.67.-a, 42.50.Ar, 89.70.+C

Quantum image sharpness estimation based on the Laplacian operator

2020 ◽  
Vol 18 (03) ◽  
pp. 2050008 ◽  
Author(s):  
She-Xiang Jiang ◽  
Ri-Gui Zhou ◽  
Wen-Wen Hu
Keyword(s):  
Laplacian Operator ◽  
The Novel ◽  
Superposition State ◽  
Image Sharpness ◽  
Quantum Superposition ◽  
Quantum Image ◽  
Essential Idea ◽  
Execution Speed ◽  
The Mean ◽  
Classical Image

In order to solve the high complexity of classical image processing, a quantum scheme for image sharpness estimation based on the Laplacian operator is proposed. The mean of grayscale gradients of all pixels is regarded as the sharpness estimation metric. A new quantum image representation model is presented by extending the Novel Enhanced Quantum Representation (NEQR) model, which is greatly useful for quantum image convolution. In quantum platforms, it has been shown that the mean calculation of numbers is rather difficult because the numbers are stored in a quantum superposition state. In order to solve this problem, we put forward an algorithm which essential idea is cyclically shifting the superposition state and iteratively calculating the mean of the new one and the original state. The mean can be obtained from the superposition state by only one quantum measurement. By analyzing the space complexity and time complexity, the scheme is far superior to classical ones in terms of resource consumption and execution speed. In addition, the results of simulation experiments show that for noiseless images, the performance of the scheme is consistent with subjective visual perception of images sharpness.

QUANTUM COMPUTATION FOR ACTION SELECTION USING REINFORCEMENT LEARNING

2006 ◽  
Vol 04 (06) ◽  
pp. 1071-1083 ◽  
Author(s):  
C. L. CHEN ◽  
D. Y. DONG ◽  
Z. H. CHEN
Keyword(s):  
Decision Making ◽  
Quantum Theory ◽  
Reinforcement Learning ◽  
Quantum Computation ◽  
Action Selection ◽  
Selection Method ◽  
Superposition State ◽  
Exploration And Exploitation ◽  
Quantum Superposition ◽  
State Action

This paper proposes a novel action selection method based on quantum computation and reinforcement learning (RL). Inspired by the advantages of quantum computation, the state/action in a RL system is represented with quantum superposition state. The probability of action eigenvalue is denoted by probability amplitude, which is updated according to rewards. And the action selection is carried out by observing quantum state according to collapse postulate of quantum measurement. The results of simulated experiments show that quantum computation can be effectively used to action selection and decision making through speeding up learning. This method also makes a good tradeoff between exploration and exploitation for RL using probability characteristics of quantum theory.

scholarly journals Emergence of the Macroscopic Quantum Superposition State in Microtubules

2013 ◽  
Vol 04 (06) ◽  
pp. 734-737
Author(s):  
Tongcheng Wu ◽  
Keming Ren ◽  
Xijun Qiu
Keyword(s):  
Superposition State ◽  
Quantum Superposition ◽  
Macroscopic Quantum
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