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Numerically we simulate the effect of optimized coherent control pulses with a finite duration on a qubit in a bath of spins. The pulses of finite duration are compared with ideal instantaneous pulses. In particular, we show that properly…

Quantum Physics · Physics 2008-08-26 P. Karbach , S. Pasini , G. S. Uhrig

Coherent carrier control in quantum nanostructures is studied within the framework of Optimal Control. We develop a general solution scheme for the optimization of an external control (e.g., lasers pulses), which allows to channel the…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 Alfio Borzi , Georg Stadler , Ulrich Hohenester

Quantum machine learning (QML) is promising for potential speedups and improvements in conventional machine learning (ML) tasks (e.g., classification/regression). The search for ideal QML models is an active research field. This includes…

Quantum Physics · Physics 2022-02-07 Mahabubul Alam , Swaroop Ghosh

Along with the scaling of dimensions in quantum systems, transitions between the system's energy levels would become close in frequency, which are conventionally resolved by weak and lengthy pulses. Here, we extend and experimentally…

Quantum control is a ubiquitous research field that has enabled physicists to delve into the dynamics and features of quantum systems, delivering powerful applications for various atomic, optical, mechanical, and solid-state systems. In…

Quantum Physics · Physics 2023-12-11 Ariel Norambuena , Marios Mattheakis , Francisco J. González , Raúl Coto

Auto-correlated noise appears in many solid state qubit systems and hence needs to be taken into account when developing gate operations for quantum information processing. However, explicitly simulating this kind of noise is often less…

Ising interaction between qubits could produce distortion in entangled pairs generated for engineering purposes (as in quantum computation) in presence of parasite magnetic fields, destroying or altering the expected behavior of process in…

Quantum Physics · Physics 2013-05-29 Francisco Delgado

Neural networks are a promising tool for characterizing intermediate-scale quantum devices from limited amounts of measurement data. A challenging problem in this area is to learn the action of an unknown quantum process on an ensemble of…

Quantum Physics · Physics 2023-12-06 Yan Zhu , Ya-Dong Wu , Qiushi Liu , Yuexuan Wang , Giulio Chiribella

An optimal dynamical decoupling of a quantum system coupled to a noisy environment must take into account also the imperfections of the control pulses. We present a new formalism which describes, in a closed-form expression, the evolution…

Quantum Physics · Physics 2016-10-19 Ido Almog , Gil Loewenthal , Jonathan Coslovsky , Yoav Sagi , Nir Davidson

High fidelity coherent control of quantum systems is critical to building quantum devices and quantum computers. We provide a general optimal control framework for designing control sequences that account for hardware control distortions…

Quantum Physics · Physics 2015-08-26 Ian N. Hincks , Christopher Granade , Troy W. Borneman , D. G. Cory

Composite pulses are a quantum control technique for canceling out systematic control errors. We present a new composite pulse sequence inspired by quantum search. Our technique can correct a wider variety of systematic errors -- including,…

Quantum Physics · Physics 2007-05-23 Ben W. Reichardt , Lov K. Grover

Several methods are proposed for the analysis, visualization and interpretation of high-dimensional spin system trajectories produced by quantum mechanical simulations. It is noted that expectation values of specific observables in large…

Quantum Physics · Physics 2014-07-16 Ilya Kuprov

Fifty years of developments in nuclear magnetic resonance (NMR) have resulted in an unrivaled degree of control of the dynamics of coupled two-level quantum systems. This coherent control of nuclear spin dynamics has recently been taken to…

Quantum Physics · Physics 2015-06-26 Lieven M. K. Vandersypen , Isaac L. Chuang

Pulse controlled non-adiabatic quantum state transmission (QST) was proposed many years ago. However, in practice environmental noise inevitably damages communication quality in the proposal. In this paper, we study the optimally controlled…

Quantum Physics · Physics 2023-09-26 Xiang-Han Liang , Lian-Ao Wu , Zhao-Ming Wang

We investigate several control strategies for the transport of an excitation along a spin chain. We demonstrate that fast, high fidelity transport can be achieved using protocols designed with differentiable programming. Building on this,…

Quantum Physics · Physics 2022-11-30 Luuk Coopmans , Steve Campbell , Gabriele De Chiara , Anthony Kiely

Long-time dynamical decoupling and quantum control of qubits require high-precision control pulses. Full characterization (quantum tomography) of imperfect pulses presents a bootstrap problem: tomography requires initial states of a qubit…

Quantum Physics · Physics 2015-05-18 V. V. Dobrovitski , G. de Lange , D. Ristè , R. Hanson

In this paper, we synthesize two aperiodic-sampled deep neural network (DNN) control schemes, based on the closed-loop tracking stability guarantees. By means of the integral quadratic constraint coping with the input-output behaviour of…

Systems and Control · Electrical Eng. & Systems 2025-06-24 Renjie Ma , Zhijian Hu , Rongni Yang , Ligang Wu

A quantum neural network (QNN) is a parameterized mapping efficiently implementable on near-term Noisy Intermediate-Scale Quantum (NISQ) computers. It can be used for supervised learning when combined with classical gradient-based…

Quantum Physics · Physics 2023-03-28 Xuchen You , Shouvanik Chakrabarti , Boyang Chen , Xiaodi Wu

Quantum network research at both the software stack and hardware implementation level has become an exciting area of quantum information science. Although demonstrations of small-scale quantum networks have emerged in the past decade,…

Quantum Physics · Physics 2024-12-13 Huiping Lin , Ruixuan Deng , Chris Z. Yao , Zhengfeng Ji , Mingsheng Ying

In multi-qubit system, correlated errors subject to unwanted interactions with other qubits is one of the major obstacles for scaling up quantum computers to be applicable. We present two approaches to correct such noise and demonstrate…

Quantum Physics · Physics 2021-03-16 Xiu-Hao Deng , Yong-Ju Hai , Jun-Ning Li , Yao Song