scholarly journals Quantum control with a multi-dimensional Gaussian quantum invariant

Quantum ◽  
2021 ◽  
Vol 5 ◽  
pp. 409
Author(s):  
Selwyn Simsek ◽  
Florian Mintert
Keyword(s):  
Information Technology ◽  
Quantum Information ◽  
Control Problem ◽  
Ground State ◽  
Quantum Control ◽  
Spatial Dimension ◽  
Time Dependent ◽  
Quantum Invariants ◽  
Quantum Invariant ◽  
Trapped Ion

The framework of quantum invariants is an elegant generalization of adiabatic quantum control to control fields that do not need to change slowly. Due to the unavailability of invariants for systems with more than one spatial dimension, the benefits of this framework have not yet been exploited in multi-dimensional systems. We construct a multi-dimensional Gaussian quantum invariant that permits the design of time-dependent potentials that let the ground state of an initial potential evolve towards the ground state of a final potential. The scope of this framework is demonstrated with the task of shuttling an ion around a corner which is a paradigmatic control problem in achieving scalability of trapped ion quantum information technology.

scholarly journals Quantum Control and Quantum Information Technology

2013 ◽  
Vol 2013 ◽  
pp. 1-2 ◽  
Author(s):  
Daoyi Dong ◽  
Chunlin Chen ◽  
Min Jiang ◽  
Lin-Cheng Wang
Keyword(s):  
Information Technology ◽  
Quantum Information ◽  
Quantum Control

scholarly journals INFORMATION-TECHNOLOGY APPROACH TO QUANTUM FEEDBACK CONTROL

2006 ◽  
Vol 20 (11n13) ◽  
pp. 1304-1316 ◽  
Author(s):  
DAO-YI DONG ◽  
CHEN-BIN ZHANG ◽  
ZONG-HAI CHEN ◽  
CHUN-LIN CHEN
Keyword(s):  
Information Technology ◽  
Quantum Information ◽  
Feedback Control ◽  
Information Acquisition ◽  
Quantum Control ◽  
State Recognition ◽  
Feedback Scheme ◽  
Quantum Control Theory ◽  
Quantum Feedback ◽  
Control Step

Quantum control theory is profitably reexamined from the perspective of quantum information, two results on the role of quantum information technology in quantum feedback control are presented and two quantum feedback control schemes, teleportation-based distant quantum feedback control and quantum feedback control with quantum cloning, are proposed. In the first feedback scheme, the output from the quantum system to be controlled is fed back into the distant actuator via teleportation to alter the dynamics of system. The result theoretically shows that it can accomplish some tasks such as distant feedback quantum control that Markovian or Bayesian quantum feedback can not complete. In the second feedback strategy, the design of quantum feedback control algorithms is separated into a state recognition step, which gives "on-off" signal to the actuator through recognizing some copies from the cloning machine, and a feedback (control) step using another copies of cloning machine. A compromise between information acquisition and measurement disturbance is established, and this strategy can perform some quantum control tasks with coherent feedback.

scholarly journals Quantum information technology

2003 ◽  
Vol 6 (1) ◽  
pp. 30-36 ◽  
Author(s):  
Timothy P Spiller
Keyword(s):  
Information Technology ◽  
Quantum Information

A Time-Dependent Bifurcation Model with Control and Pulsing Oscillations

2003 ◽  
Vol 17 (22n24) ◽  
pp. 4260-4266
Author(s):  
Qishao Lu ◽  
Cuncai Hua
Keyword(s):  
Control Problem ◽  
Memory Effects ◽  
Time Dependent ◽  
Bifurcation Parameter ◽  
Bifurcation Transition ◽  
Delayed Bifurcation ◽  
With Memory

A time-dependent bifurcation model and its control problem are studied. Firstly, the delayed bifurcating transition with memory effects due to time-dependent parameters are analysed. Secondly, a control problem with time-dependent parametric feedback in this bifurcation model is investigated. Finally, an important mechanism for pulsing oscillation is found as the result of the delayed bifurcation transition occurring when the bifurcation parameter varies periodically across the steady bifurcation value.

THE TRAPPED-ION QUBIT: COHERENT CONTROL IN INFINITE-DIMENSIONAL QUANTUM SYSTEMS

2009 ◽  
Vol 24 (32) ◽  
pp. 2565-2578
Author(s):  
C. RANGAN
Keyword(s):  
Quantum Computing ◽  
Quantum System ◽  
Quantum Control ◽  
Coherent Control ◽  
Quantum Information Processing ◽  
Quantum Systems ◽  
Infinite Dimensional ◽  
Trapped Ion ◽  
Rich Variety ◽  
Control Research

Theories of quantum control have, until recently, made the assumption that the Hilbert space of a quantum system can be truncated to finite dimensions. Such truncations, which can be achieved for most quantum systems via bandwidth restrictions, have enabled the development of a rich variety of quantum control and optimal control schemes. Recent studies in quantum information processing have addressed the control of infinite-dimensional quantum systems such as the quantum states of a trapped-ion. Controllability in an infinite-dimensional quantum system is hard to prove with conventional methods, and infinite-dimensional systems provide unique challenges in designing control fields. In this paper, we will discuss the control of a popular system for quantum computing the trapped-ion qubit. This system, modeled by a spin-half particle coupled to a quantized harmonic oscillator, is an example for a surprisingly rich variety of control problems. We will show how this infinite-dimensional quantum system can be examined via the lens of the Finite Controllability Theorem, two-color STIRAP, the generalized Heisenberg system, etc. These results are important from the viewpoint of developing more efficient quantum control protocols, particularly in quantum computing systems. This work shows how one can expand the scope of quantum control research to beyond that of finite-dimensional quantum systems.

scholarly journals Optimal collection of radiation emitted by a trapped atomic ensemble

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Árpád Kurkó ◽  
Peter Domokos ◽  
András Vukics ◽  
Thomas Bækkegaard ◽  
Nikolaj Thomas Zinner ◽  
...  
Keyword(s):  
Quantum Information ◽  
Density Distribution ◽  
Ground State ◽  
Cold Atoms ◽  
Information Storage ◽  
Atomic Ensemble ◽  
Normal Density ◽  
Atomic Ensembles ◽  
Optical Photons ◽  
Electronic Ground

AbstractTrapped atomic ensembles are convenient systems for quantum information storage in the long-lived sublevels of the electronic ground state and its conversion to propagating optical photons via stimulated Raman processes. Here we investigate a phase-matched emission of photons from a coherently prepared atomic ensemble. We consider an ensemble of cold atoms in an elongated harmonic trap with normal density distribution, and determine the parameters of paraxial optics to match the mode geometry of the emitted radiation and optimally collect it into an optical waveguide.

An Introduction to Time-Resolved Pump/Probe Spectroscopy

1985 ◽  
Vol 39 (3) ◽  
pp. 444-451 ◽  
Author(s):  
F. E. Lytle ◽  
R. M. Parrish ◽  
W. T. Barnes
Keyword(s):  
Absorption Spectra ◽  
Ground State ◽  
Fluorescence Spectra ◽  
Excited State Absorption ◽  
Time Dependent ◽  
Triplet Excited State ◽  
Ground State Absorption ◽  
Time Resolved ◽  
Pump Probe ◽  
Probe Spectroscopy

The construction and operating principles of a two-color pump/probe spectrometer are described. This instrument is capable of obtaining ground-state absorption spectra, both singlet-singlet and triplet-triplet excited-state absorption spectra, photoproduct spectra, and stimulated fluorescence spectra. In addition, time-dependent measurements can be made with an impulse response of 250 ps and a free temporal range of 13 ns.

scholarly journals High-Fidelity Preservation of Quantum Information During Trapped-Ion Transport

2018 ◽  
Vol 120 (1) ◽  
Author(s):  
Peter Kaufmann ◽  
Timm F. Gloger ◽  
Delia Kaufmann ◽  
Michael Johanning ◽  
Christof Wunderlich
Keyword(s):  
Quantum Information ◽  
Ion Transport ◽  
High Fidelity ◽  
Trapped Ion

Phase control for entanglement preparation in two-qubit systems

2005 ◽  
Vol 5 (4&5) ◽  
pp. 364-379
Author(s):  
V.S. Malinovsky ◽  
I.R. Sola
Keyword(s):  
Quantum Information ◽  
Quantum Computation ◽  
Quantum Control ◽  
Phase Control ◽  
Adiabatic Passage ◽  
Pulse Parameters ◽  
Qubit System ◽  
Phase Manipulation ◽  
Laser Control ◽  
Pi Pulses

The theory of Quantum Control is starting to lay bridges with the field of Quantum Information and Quantum Computation. Using key ideas of laser control of the dynamics by means of phase manipulation and adiabatic passage, we review laser schemes that allow entanglement preparation in a two-qubit system. The schemes are based on sequences that use four time-delayed pulses, with or without concerted decay, in or off resonance with the intermediate levels of the qubit space. We show how to control the fidelity and phase of the entanglement, as well as the sensitivity of the preparation to the different pulse parameters. In general the schemes provide an improvement in robustness and in the finesse of the control to phase, with respect to previously proposed schemes based on sequences of $\pi$ pulses.

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