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Quantum parameter estimation has many applications, from gravitational wave detection to quantum key distribution. We present the first experimental demonstration of the time-symmetric technique of quantum smoothing. We consider both…

The signal to noise ratio of quantum sensing protocols scales with the square root of the coherence time. Thus, increasing this time is a key goal in the field. Dynamical decoupling has proven to be efficient in prolonging the coherence…

Quantum Physics · Physics 2015-06-17 Gilad Arrad , Yuval Vinkler , Dorit Aharonov , Alex Retzker

The ambition of harnessing the quantum for computation is at odds with the fundamental phenomenon of decoherence. The purpose of quantum error correction (QEC) is to counteract the natural tendency of a complex system to decohere. This…

We present a quantum algorithm to estimate parameters at the quantum metrology limit using deterministic quantum computation with one bit. When the interactions occurring in a quantum system are described by a Hamiltonian $H= \theta H_0$,…

Quantum Physics · Physics 2008-07-03 Rolando D. Somma , Sergio Boixo

We introduce new measures of decoherence appropriate for evaluation of quantum computing designs. Environment-induced deviation of a quantum system's evolution from controlled dynamics is quantified by a single numerical measure. This…

Mesoscale and Nanoscale Physics · Physics 2010-10-12 Leonid Fedichkin , Arkady Fedorov , Vladimir Privman

Quantum coherence is the key resource for quantum technology, with applications in quantum optics, information processing, metrology and cryptography. Yet, there is no universally efficient method for quantifying coherence either in…

Quantum Physics · Physics 2014-10-24 Davide Girolami

We introduce the quantitative measures characterizing the rates of decoherence and thermalization of quantum systems. We study the time evolution of these measures in the case of a quantum harmonic oscillator whose relaxation is described…

Quantum Physics · Physics 2009-11-06 V. V. Dodonov , S. S. Mizrahi , A. L. de Souza Silva

A major goal of developing high-precision control of many-body quantum systems is to realise their potential as quantum computers. Probably the most significant obstacle in this direction is the problem of "decoherence": the extreme…

Certain physical aspects of quantum error correction are discussed for a quantum computer (n-qubit register) in contact with a decohering environment. Under rather plausible assumptions upon the form of the computer-environment interaction,…

Quantum Physics · Physics 2008-02-03 M. Biskup , P. Cejnar , R. Kotecky

Due to omnipresent environmental interferences, quantum coherences inevitably undergo irreversible transformations over certain time-scales, thus leading to the loss of encoded information. This process, known as decoherence, has been a…

Quantum Physics · Physics 2014-06-19 Swathi S. Hegde , T. S. Mahesh

Quantum sensing harnesses the unique properties of quantum systems to enable precision measurements of physical quantities such as time, magnetic and electric fields, acceleration, and gravitational gradients well beyond the limits of…

Quantum Physics · Physics 2025-07-23 Ivana Nikoloska , Ruud Van Sloun , Osvaldo Simeone

We compare approaches to evaluation of decoherence at low temperatures in two-state quantum systems weakly coupled to the environment. By analyzing an exactly solvable model, we demonstrate that a non-Markovian approximation scheme yields…

Mesoscale and Nanoscale Physics · Physics 2010-10-12 Dmitry Solenov , Vladimir Privman

There are several important solid-state systems, such as defects in solids, superconducting circuits and molecular qubits, for attractive candidates of quantum computations. Molecular qubits, which benefit from the power of chemistry for…

Quantum Physics · Physics 2017-06-29 Yingqiu Dai , Zhifu Shi , Yue Fu , Xi Qin , Shiwei Mu , Yang Wu , Ji-Hu Su , Lei Qin , Yuan-Qi Zhai , Yi-Fei Deng , Xing Rong , Jiangfeng Du

We investigate critical quantum metrology,that is the estimation of parameters in many-body systems close to a quantum critical point, through the lens of Bayesian inference theory. We first derive a no-go result stating that any…

Quantum Physics · Physics 2023-10-31 Raffaele Salvia , Mohammad Mehboudi , Martí Perarnau-Llobet

Decoherence of quantum states is a major hurdle towards scalable and reliable quantum computing. Lower decoherence (i.e., higher fidelity) can alleviate the error correction overhead and obviate the need for energy-intensive noise reduction…

Emerging Technologies · Computer Science 2019-04-10 Abdullah Ash Saki , Mahabubul Alam , Swaroop Ghosh

Quantum phase estimation is a paradigmatic problem in quantum sensing andmetrology. Here we show that adaptive methods based on classical machinelearning algorithms can be used to enhance the precision of quantum phase estimation when noisy…

Quantum Physics · Physics 2021-09-01 Nelson Filipe Costa , Yasser Omar , Aidar Sultanov , Gheorghe Sorin Paraoanu

The construction of large, coherent quantum systems necessary for quantum computation remains an entreating but elusive goal, due to the ubiquitous nature of decoherence. Recent progress in quantum error correction schemes have given new…

Quantum Physics · Physics 2008-02-03 Isaac L. Chuang , Yoshihisa Yamamoto

We study a decoherence reduction scheme that involves an intermediate measurement on the qubit in an equal superposition basis, in the general framework of all qubit-environment interactions that lead to qubit pure decoherence. We show…

Quantum Physics · Physics 2024-02-22 Bartosz Rzepkowski , Katarzyna Roszak

Bayesian inference is a widely used technique for real-time characterization of quantum systems. It excels in experimental characterization in the low data regime, and when the measurements have degrees of freedom. A decisive factor for its…

Quantum Physics · Physics 2025-07-10 Alexandra Ramôa , Raffaele Santagati , Nathan Wiebe

Building high-fidelity quantum computers requires efficient methods for the characterization of gate errors that provide actionable information that may be fed back into engineering efforts. Extraction of realistic error models is also…

Quantum Physics · Physics 2024-02-28 Jeffrey M. Epstein