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We explore reachable sets of open $n$-qubit quantum systems, the coherent parts of which are under full unitary control and that have just one qubit whose Markovian noise amplitude can be modulated in time such as to provide an additional…

Quantum Physics · Physics 2015-03-20 V. Bergholm , T. Schulte-Herbrueggen

A systematic approach to design robust control protocols against the influence of different types of noise is introduced. We present control schemes which protect the decay of the populations avoiding dissipation in the adiabatic and…

Quantum Physics · Physics 2018-03-14 Amikam Levy , A. Kiely , J. G. Muga , R. Kosloff , E. Torrontegui

Quantum computers hold immense potential in the field of chemistry, ushering new frontiers to solve complex many body problems that are beyond the reach of classical computers. However, noise in the current quantum hardware limits their…

Quantum Physics · Physics 2024-03-20 Chayan Patra , Sonaldeep Halder , Rahul Maitra

Decoherence-free subspace (DFS) provides a crucial mechanism for passive error mitigation in quantum computation by encoding information within symmetry-protected subspaces of the Hilbert space, which are immune from collective decoherence.…

Quantum Physics · Physics 2025-09-16 Zi-Ming Li , Yu-xi Liu

We present a theoretical proposal for preparing and manipulating a state of a single continuous-variable degree of freedom confined to a nonharmonic potential. By utilizing optimally controlled modulation of the potential's position and…

Quantum Physics · Physics 2025-08-13 Piotr T. Grochowski , Hannes Pichler , Cindy A. Regal , Oriol Romero-Isart

Achieving unit fidelity in quantum state preparation is often impossible in the presence of environmental decoherence. While continuous monitoring and feedback control can improve fidelity, perfect state preparation remains elusive in many…

Quantum Physics · Physics 2025-07-02 Eoin O'Connor , Hailan Ma , Marco G. Genoni

We develop connections between generalised notions of entanglement and quantum computational devices where the measurements available are restricted, either because they are noisy and/or because by design they are only along Pauli…

Quantum Physics · Physics 2012-01-18 N. Ratanje , S. Virmani

In the scale-up of quantum computers, the framework underpinning fault-tolerance generally relies on the strong assumption that environmental noise affecting qubit logic is uncorrelated (Markovian). However, as physical devices progress…

This work develops measures for quantifying the effects of field noise upon targeted unitary transformations. Robustness to noise is assessed in the framework of the quantum control landscape, which is the mapping from the control to the…

Robust performance of control schemes for open quantum systems is investigated under classical uncertainties in the generators of the dynamics and nonclassical uncertainties due to decoherence and initial state preparation errors. A…

Optimization and Control · Mathematics 2024-06-24 Sophie G. Schirmer , Frank C. Langbein , Carrie A. Weidner , Edmond Jonckheere

We develop a model-free framework for stabilizing quantum states using only empirical finite-difference evaluations of a measurement-derived Lyapunov observable. The controller requires no knowledge of the Hamiltonian, dissipative…

Quantum Physics · Physics 2026-04-14 Robert Vrabel

Quantum state preparation, a crucial subroutine in quantum computing, involves generating a target quantum state from initialized qubits. Arbitrary state preparation algorithms can be broadly categorized into arithmetic decomposition (AD)…

Accurate and efficient quantum control in the presence of constraints and decoherence is a requirement and a challenge in quantum information processing. Shortcuts to adiabaticity, originally proposed to speed up slow adiabatic process,…

The problem of automatically protecting a quantum system against noise in a closed circuit is analyzed. A general scheme is developed built from two steps. At first, a distillation step is induced in which undesired components are removed…

Quantum Physics · Physics 2009-11-11 S. Kallush , R. Kosloff

A closed quantum system is defined as completely controllable if an arbitrary unitary transformation can be executed using the available controls. In practice, control fields are a source of unavoidable noise, which has to be suppressed to…

Quantum Physics · Physics 2015-06-17 S. Kallush , M. Khasin , R. Kosloff

The development of efficient algorithms that generate robust quantum controls is crucial for the realization of quantum technologies. The commonly used gradient-based optimization algorithms are limited by their sensitivity to the initial…

Quantum Physics · Physics 2021-12-03 M. Harshanth Ram , V. R. Krithika , Priya Batra , T. S. Mahesh

Robustness and reliability are two key requirements for developing practical quantum control systems. The purpose of this paper is to design a coherent feedback controller for a class of linear quantum systems suffering from Markovian…

Quantum Physics · Physics 2020-03-24 Yanan Liu , Daoyi Dong , Ian R. Petersen , Qing Gao , Steven X. Ding , Shota Yokoyama , Hidehiro Yonezawa

Quantum control protocols are typically devised in the time domain, leaving their spectral behavior to emerge only a posteriori. Here, we invert this paradigm. Starting from a target frequency-domain filter, we employ the…

Quantum Physics · Physics 2025-06-23 Loris Maria Cangemi , Yoav Woldiger , Amikam Levy , Assaf Hamo

Quantum state preparation is an important subroutine in many quantum algorithms. The goal is to encode classical information directly to the quantum state so that it is possible to leverage quantum algorithms for data processing. However,…

Quantum Physics · Physics 2026-05-01 Oskari Kerppo , William Steadman , Ossi Niemimäki , Valtteri Lahtinen

We propose a general scheme for dissipatively preparing arbitrary pure quantum states on a multipartite qubit register in a finite number of basic control blocks. Our "splitting-subspace" approach relies on control resources that are…

Quantum Physics · Physics 2013-11-19 Giacomo Baggio , Francesco Ticozzi , Lorenza Viola