scholarly journals Dynamically corrected gates from geometric space curves

2021 ◽  
Author(s):  
Edwin Barnes ◽  
Fernando Calderon-Vargas ◽  
Wenzheng Dong ◽  
Bikun Li ◽  
Junkai Zeng ◽  
...  
Keyword(s):  
Quantum Information ◽  
Information Technologies ◽  
Solution Space ◽  
Quantum Systems ◽  
Quantum Evolution ◽  
General Technique ◽  
Control Techniques ◽  
Space Curves ◽  
Close Relationship ◽  
Geometric Space

Abstract Quantum information technologies demand highly accurate control over quantum systems. Achieving this requires control techniques that perform well despite the presence of decohering noise and other adverse effects. Here, we review a general technique for designing control fields that dynamically correct errors while performing operations using a close relationship between quantum evolution and geometric space curves. This approach provides access to the global solution space of control fields that accomplish a given task, facilitating the design of experimentally feasible gate operations for a wide variety of applications.

scholarly journals Frequency Dependence of the Entanglement Entropy Production in a System of Coupled Driven Nonlinear Oscillators

Entropy ◽  
2019 ◽  
Vol 21 (9) ◽  
pp. 889
Author(s):  
Shi-Hui Zhang ◽  
Zhan-Yuan Yan
Keyword(s):  
Quantum Information ◽  
Nonlinear Systems ◽  
Entropy Production ◽  
Information Technologies ◽  
Energy Levels ◽  
Entanglement Entropy ◽  
Nonlinear Oscillators ◽  
Quantum Evolution ◽  
Driving Frequency ◽  
The Impact

Driven nonlinear systems have attracted great interest owing to their applications in quantum technologies such as quantum information. In quantum information, entanglement is a vital resource and can be measured by entropy in bipartite systems. In this paper, we carry out an investigation to study the impact of driving frequency on the entanglement with a bipartite system of two coupled driven nonlinear oscillators. It is numerically found that the time evolution of the entanglement entropy between the subsystems significantly depends on the driving frequency. The dependence curve of the entropy production on the driving frequency exhibits a pronounced peak. This means the entanglement between the subsystems can be greatly increased by tuning the driving frequency. Further analyses show that the enhancement of the entropy production by the driving frequency is closely related to the energy levels involved in the quantum evolution. This is confirmed by the results related to the quantum spectrum and the dispersion of the wave function in the phase space. Our work gives a convenient way to enhance the entanglement in driven nonlinear systems and throws light on the role of driven nonlinear systems in quantum information technologies.

scholarly journals Convergence Rates for Quantum Evolution and Entropic Continuity Bounds in Infinite Dimensions

2019 ◽  
Vol 374 (2) ◽  
pp. 823-871 ◽  
Author(s):  
Simon Becker ◽  
Nilanjana Datta
Keyword(s):  
Convergence Rates ◽  
Lipschitz Continuity ◽  
Open Quantum Systems ◽  
High Energy ◽  
Quantum Systems ◽  
Quantum Evolution ◽  
Infinite Dimensions ◽  
Quantum Brownian Motion ◽  
Infinite Dimensional ◽  
Energy Constrained

Abstract By extending the concept of energy-constrained diamond norms, we obtain continuity bounds on the dynamics of both closed and open quantum systems in infinite dimensions, which are stronger than previously known bounds. We extensively discuss applications of our theory to quantum speed limits, attenuator and amplifier channels, the quantum Boltzmann equation, and quantum Brownian motion. Next, we obtain explicit log-Lipschitz continuity bounds for entropies of infinite-dimensional quantum systems, and classical capacities of infinite-dimensional quantum channels under energy-constraints. These bounds are determined by the high energy spectrum of the underlying Hamiltonian and can be evaluated using Weyl’s law.

scholarly journals Topological protection of biphoton states

Science ◽  
2018 ◽  
Vol 362 (6414) ◽  
pp. 568-571 ◽  
Author(s):  
Andrea Blanco-Redondo ◽  
Bryn Bell ◽  
Dikla Oren ◽  
Benjamin J. Eggleton ◽  
Mordechai Segev
Keyword(s):  
Quantum Information ◽  
Thermal Environment ◽  
Propagation Constant ◽  
Quantum Systems ◽  
Quantum Gates ◽  
Scattering Loss ◽  
Spatial Features ◽  
Quantum Optical ◽  
Nontrivial Topology ◽  
Large Quantum

The robust generation and propagation of multiphoton quantum states are crucial for applications in quantum information, computing, and communications. Although photons are intrinsically well isolated from the thermal environment, scaling to large quantum optical devices is still limited by scattering loss and other errors arising from random fabrication imperfections. The recent discoveries regarding topological phases have introduced avenues to construct quantum systems that are protected against scattering and imperfections. We experimentally demonstrate topological protection of biphoton states, the building block for quantum information systems. We provide clear evidence of the robustness of the spatial features and the propagation constant of biphoton states generated within a nanophotonics lattice with nontrivial topology and propose a concrete path to build robust entangled states for quantum gates.

scholarly journals Educational tourism as pedagogical innovation in conditions of virtual environment

2021 ◽  
Vol 102 (2) ◽  
pp. 7-17
Author(s):  
T. Shumeiko ◽  
◽  
G. Baubekova ◽  
Keyword(s):  
Virtual Environment ◽  
Information And Communication Technologies ◽  
Information Technologies ◽  
Tourism Industry ◽  
Digital Resources ◽  
Pedagogical Innovation ◽  
Innovation In Education ◽  
Educational Tourism ◽  
Close Relationship ◽  
Internationalization Of Education

This article is substantiating the relevance of the development of educational tourism caused by the trends of globalization and internationalization of education. The analysis of scientific works on the research of educational tourism is presented. It is noted that despite the relatively long history of the existence of some forms of educational tourism, taking into account the views of scientists that innovation in education is not always a completely new phenomenon, educational tourism can be considered a pedagogical innovation. According to the authors, the existing conviction of scientists about the close relationship of pedagogical innovations with information technologies enhances the innovativeness of virtual educational tourism. The periodization of educational tourism from antiquity to the present day is presented. The significant impact of travels for knowledge and academic exchanges on the modern infrastructure of the tourism industry is noted. Indicating the role of educational tourism for the development of international cooperation in education, the authors analyze the dynamics of external and internal academic mobility in the period from 2015 to 2019 years at the Kostanay State Pedagogical University, which now is Kostanay Regional University named after A. Baitursynov. The innovative nature of modern educational tourism, which is enhanced by the use of information and communication technologies and digital resources, along with traditional forms of tourist and educational activities, is emphasized. A virtual excursion is considered as one of the innovative forms of education. The experience of the participation of students of pedagogical specialties in the development and implementation of digital resources in secondary schools in a virtual environment, contributing to the formation of the readiness of future teachers for productive activities in the context of distance education, is presented.

scholarly journals Probing Many-Body Systems Near Spectral Degeneracies

Symmetry ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1796
Author(s):  
Klaus Ziegler
Keyword(s):  
Decay Rate ◽  
Correlation Matrix ◽  
Time Correlation ◽  
General Concept ◽  
Quantum Systems ◽  
Quantum Evolution ◽  
Many Body ◽  
Space Localization ◽  
Many Body Systems ◽  
Random Times

The diagonal elements of the time correlation matrix are used to probe closed quantum systems that are measured at random times. This enables us to extract two distinct parts of the quantum evolution, a recurrent part and an exponentially decaying part. This separation is strongly affected when spectral degeneracies occur, for instance, in the presence of spontaneous symmetry breaking. Moreover, the slowest decay rate is determined by the smallest energy level spacing, and this decay rate diverges at the spectral degeneracies. Probing the quantum evolution with the diagonal elements of the time correlation matrix is discussed as a general concept and tested in the case of a bosonic Josephson junction. It reveals for the latter characteristic properties at the transition to Hilbert-space localization.

ENCRYPTION OF QUANTUM INFORMATION

2003 ◽  
Vol 14 (05) ◽  
pp. 741-755 ◽  
Author(s):  
JAN BOUDA ◽  
VLADIMÍ R. BUŽEK
Keyword(s):  
Quantum Information ◽  
Quantum Channel ◽  
Composite System ◽  
Quantum Systems ◽  
Noisy Channel ◽  
Classical Description ◽  
Quantum Analogue ◽  
Known Plaintext Attack

We study in detail the problem of encryption of quantum information. We present an attack on a private quantum channel (PQC) which applies when partial classical description of a ciphertext is known (the so-called known-ciphertext attack) and we show how this situation can be avoided. The quantum analogue of the known plaintext attack is also discussed. We determine how correlations between quantum systems can be encrypted and we conclude that two PQCs on the subsystems form a PQC on the whole composite system. Finally, some applications of the PQC are suggested and a security of a noisy channel is discussed.

Quantum cryptography

2009 ◽  
Author(s):  
Stephen Barnett
Keyword(s):  
Quantum Information ◽  
Quantum Cryptography ◽  
Quantum Key Distribution ◽  
Communication Systems ◽  
Information Technologies ◽  
Key Distribution ◽  
Julius Caesar ◽  
Secure Communications ◽  
Quantum Communications ◽  
History Of

The practical implementation of quantum information technologies requires, for the most part, highly advanced and currently experimental procedures. One exception is quantum cryptography, or quantum key distribution, which has been successfully demonstrated in many laboratories and has reached an advanced level of development. It will probably become the first commercial application of quantum information. In quantum key distribution, Alice and Bob exploit a quantum channel to create a secret shared key comprising a random string of binary digits. This key can then be used to protect a subsequent communication between them. The principal idea is that the secrecy of the key distribution is ensured by the laws of quantum physics. Proving security for practical communication systems is a challenging problem and requires techniques that are beyond the scope of this book. At a fundamental level, however, the ideas are simple and may readily be understood with the knowledge we have already acquired. Quantum cryptography is the latest idea in the long history of secure (and not so secure) communications and, if it is to develop, it will have to compete with existing technologies. For this reason we begin with a brief survey of the history and current state of the art in secure communications before turning to the possibilities offered by quantum communications. The history of cryptography is a long and fascinating one. As a consequence of the success or, more spectacularly, the failure of ciphers, wars have been fought, battles decided, kingdoms won, and heads lost. In the information age, ciphers and cryptosystems have become part of everyday life; we use them to protect our computers, to shop over the Internet, and to access our money via an ATM (automated teller machine). One of the oldest and simplest of all ciphers is the transposition or Caesarean cipher (attributed to Julius Caesar), in which the letters are shifted by a known (and secret) number of places in the alphabet. If the shift is 1, for example, then A is enciphered as B, B→C, · · ·, Y→Z, Z→A. A shift of five places leads us to make the replacements A→F, B→G, · · ·, Y→D, Z→E.

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