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Quantum Process Tomography (QPT) methods aim at identifying, i.e. estimating, a quantum process. QPT is a major quantum information processing tool, since it especially allows one to experimentally characterize the actual behavior of…

Quantum Physics · Physics 2025-06-27 Yannick Deville , Alain Deville

We present a scheme to drive a finite-dimensional quantum system into the decoherence-free subspaces(DFS) by Lyapunov control. Control fields are established by Lyapunov function. This proposal works well for both closed and open quantum…

Quantum Physics · Physics 2013-05-29 X. X. Yi , X. L. Huang , Chunfeng Wu , C. H. Oh

The accurate and reliable characterization of quantum dynamical processes underlies efforts to validate quantum technologies, where discrimination between competing models of observed behaviors inform efforts to fabricate and operate qubit…

Quantum Physics · Physics 2016-10-31 Eugene Dumitrescu , Travis S. Humble

We present a compressive quantum process tomography scheme that fully characterizes any rank-deficient completely-positive process with no a priori information about the process apart from the dimension of the system on which the process…

Decoherence is one of the most important obstacles that must be overcome in quantum information processing. It depends on the qubit-environment coupling strength, but also on the spectral composition of the noise generated by the…

Quantum Physics · Physics 2011-12-02 Gonzalo A. Alvarez , Dieter Suter

Nonadiabatic holonomic quantum computation in decoherence-free subspaces has attracted increasing attention recently, as it allows for high-speed implementation and combines both the robustness of holonomic gates and the coherence…

Quantum Physics · Physics 2017-06-12 P. Z. Zhao , G. F. Xu , Q. M. Ding , Erik Sjöqvist , D. M. Tong

We analyze the robustness of decoherence-free (DF) subspace and subsystem in charge qubits, when difference from the collective decoherence measurement condition is large in the long time period, which is applicable for solid-state qubits…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 Tetsufumi Tanamoto , Shinobu Fujita

We develop and implement a method for modeling decoherence processes on an N-dimensional quantum system that requires only an $N^2$-dimensional quantum environment and random classical fields. This model offers the advantage that it may be…

Quantum Physics · Physics 2009-11-10 G. Teklemariam , E. M. Fortunato , C. C. Lopez , J. Emerson , J. P. Paz , T. F. Havel , D. G. Cory

Dynamical decoupling is a technique that protects qubits against noise. The ability to preserve quantum coherence in the presence of noise is essential for the development of quantum devices. Here the Rigetti quantum computing platform was…

Quantum Physics · Physics 2022-02-08 Alexandre M. Souza

We introduce measures of quantum coherence as the speed of evolution of a system under decoherence. That is, coherence is the ability to estimate a dephasing channel, quantified by the quantum Fisher information. We extend the analysis to…

Quantum Physics · Physics 2019-01-23 Benjamin Yadin , Pieter Bogaert , Cristian E. Susa , Davide Girolami

Accurately establishing the state of large-scale quantum systems is an important tool in quantum information science; however, the large number of unknown parameters hinders the rapid characterisation of such states, and reconstruction…

Quantum Physics · Physics 2014-07-30 Francesco Tonolini , Susan Chan , Megan Agnew , Alan Lindsay , Jonathan Leach

We present a protocol to construct an arbitrary quantum circuit. The quantum bits (qubits) are encoded in polarisation states of single photons. They are stored in spatially separated dense media deposed in an optical cavity. Specific…

Quantum Physics · Physics 2009-11-11 N. Sangouard

We introduce protocols for designing and manipulating qubits with ultracold alkali atoms in 3D optical lattices. These qubits are formed from two-atom spin superposition states that create a decoherence-free subspace immune to stray…

Quantum Physics · Physics 2023-05-23 Mikhail Mamaev , Joseph H. Thywissen , Ana Maria Rey

The characterization of quantum processes is a key tool in quantum information processing tasks for several reasons: on one hand, it allows to acknowledge errors in the implementations of quantum algorithms; on the other, it allows to…

Quantum Physics · Physics 2018-12-12 Ignacio Perito , Augusto Roncaglia , Ariel Bendersky

Verifying the proper preparation of quantum states is essential in modern quantum information science. Various protocols have been developed to estimate the fidelity of quantum states produced by different parties. Direct fidelity…

Quantum Physics · Physics 2024-12-11 Christopher Vairogs , Bin Yan

We introduce entanglement purification protocols for d-level systems (qudits) with improved efficiency as compared to previous protocols. While we focus on protocols for bipartite systems, we also propose generalizations to multi-partite…

Quantum Physics · Physics 2018-10-17 Jorge Miguel-Ramiro , Wolfgang Dür

The quest for effective quantum feature maps for data encoding presents significant challenges, particularly due to the flat training landscapes and lengthy training processes associated with parameterised quantum circuits. To address these…

Quantum Physics · Physics 2025-08-12 Yaswitha Gujju , Romain Harang , Chao Li , Tetsuo Shibuya , Qibin Zhao

Quantum process tomography has become increasingly critical as the need grows for robust verification and validation of candidate quantum processors. Here, we present an approach for efficient quantum process tomography that uses a…

Quantum Physics · Physics 2020-03-25 L. C. G. Govia , G. J. Ribeill , D. Ristè , M. Ware , H. Krovi

In this paper, two information leakage resistant quantum dialogue (QD) protocols over a collective-noise channel are proposed. Decoherence-free subspace (DFS) is used to erase the influence from two kinds of collective noise, i.e.,…

Quantum Physics · Physics 2022-05-06 Tian-Yu Ye

The decoherence effect caused by the coupling between the system and the environment undoubtedly leads to the errors in efficient implementations of two (or three) qubit logical gates in quantum information processing. Fortunately,…

Quantum Physics · Physics 2024-05-15 Fang-Fang Du , Gang Fan , Xue-Mei Ren