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Matter-wave interferometers with micro-particles will enable the next generation of quantum sensors to probe minute quantum phase information. Therefore, estimating the loss of coherence and the degree of entanglement degradation for such…

Quantum Physics · Physics 2024-10-25 Martine Schut , Herre Bosma , MengZhi Wu , Marko Toroš , Sougato Bose , Anupam Mazumdar

We consider pure dephasing of Bell states of electron spin qubits interacting with a sparse bath of nuclear spins. Using the newly developed two-qubit generalization of cluster correlation expansion method, we calculate the spin echo decay…

Mesoscale and Nanoscale Physics · Physics 2018-10-09 Damian Kwiatkowski , Łukasz Cywiński

One of the major challenges in quantum computation has been to preserve the coherence of a quantum system against dephasing effects of the environment. The information stored in photon polarization, for example, is quickly lost due to such…

Ensembles of dopants have widespread applications in quantum technology. The miniaturization of corresponding devices is however hampered by dipolar interactions that reduce the coherence at increased dopant density. We theoretically and…

Quantum Physics · Physics 2021-07-19 Benjamin Merkel , Pablo Cova Fariña , Andreas Reiserer

Here we demonstrate how the standard, temporal-only, dynamical-decoupling-based noise spectroscopy method can be extended to also encompass the spatial degree of freedom. This spatiotemporal spectroscopy utilizes a system of multiple qubits…

Quantum Physics · Physics 2019-04-19 Jan Krzywda , Piotr Szańkowski , Łukasz Cywiński

We consider a qubit coupled to a nonlinear quantum oscillator, the latter coupled to an Ohmic bath, and investigate the qubit dynamics. This composed system can be mapped onto that of a qubit coupled to an effective bath. An approximate…

Quantum Physics · Physics 2015-05-20 Carmen Vierheilig , Dario Bercioux , Milena Grifoni

Implementing precise operations on quantum systems is one of the biggest challenges for building quantum devices in a noisy environment. Dynamical decoupling (DD) attenuates the destructive effect of the environmental noise, but so far it…

Quantum Physics · Physics 2015-06-16 Jingfu Zhang , Alexandre M. Souza , Frederico Dias Brandao , Dieter Suter

The excellent sensitivities of quantum sensors are a double-edged sword: minuscule quantities can be observed, but any undesired signal acts as noise. This is challenging when detecting quantities that are obscured by such noise. Decoupling…

Spectral characterization of noise environments that lead to the decoherence of qubits is critical to developing robust quantum technologies. While dynamical decoupling offers one of the most successful approaches to characterize noise…

Quantum Physics · Physics 2024-05-21 Arian Vezvaee , Nanako Shitara , Shuo Sun , Andrés Montoya-Castillo

Quantum annealing is a framework for solving combinatorial optimization problems. While it offers a promising path towards a practical application of quantum hardware, its performance in real-world devices is severely limited by…

We study the current noise spectrum of qubits under transport conditions in a dissipative bosonic environment. We combine (non-)Markovian master equations with correlation functions in Laplace-space to derive a noise formula for both weak…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 R. Aguado , T. Brandes

We demonstrate the suppression of photon shot noise dephasing in a superconducting qubit by eliminating its dispersive coupling to the readout cavity. This is achieved in a tunable coupling qubit, where the qubit frequency and coupling rate…

Quantum Physics · Physics 2017-01-23 Gengyan Zhang , Yanbing Liu , James J. Raftery , Andrew A. Houck

We investigate the time-evolution of a charge qubit subject to quantum telegraph noise produced by a single electronic defect level. We obtain results for the time-evolution of the coherence that are strikingly different from the usual case…

Mesoscale and Nanoscale Physics · Physics 2008-06-25 Benjamin Abel , Florian Marquardt

Recent experiments by F. Yoshihara et al. [Phys. Rev. Lett. 97, 167001 (2006)] and by K. Kakuyanagi et al. (cond-mat/0609564) provided information on decoherence of the echo signal in Josephson-junction flux qubits at various bias…

Superconductivity · Physics 2009-11-11 Y. M. Galperin , B. L. Altshuler , J. Bergli , D. Shantsev , V. Vinokur

Unwanted interaction between a quantum system and its fluctuating environment leads to decoherence and is the primary obstacle to establishing a scalable quantum information processing architecture. Strategies such as environmental and…

We consider quantum decoherence in solid-state systems by studying the transverse dynamics of a single qubit interacting with a fermionic bath and driven by external pulses. Our interest is in investigating the extent to which the lost…

Mesoscale and Nanoscale Physics · Physics 2008-07-10 R. M. Lutchyn , L. Cywinski , Cody P. Nave , S. Das Sarma

We study a model of dephasing (decoherence) in a two-state quantum system (qubit) coupled to a bath of harmonic oscillators. An exact analytic solution for the reduced dynamics of a two-state system in this model has been obtained…

Quantum Physics · Physics 2015-05-28 V. G. Morozov , S. Mathey , G. Röpke

A spin-echo-type technique is applied to an artificial two-level system that utilizes charge degree of freedom in a small superconducting electrode. Gate-voltage pulses are used to produce the necessary pulse sequence in order to eliminate…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 Y. Nakamura , Yu. A. Pashkin , T. Yamamoto , J. S. Tsai

Stroboscopic spin flips have already been shown to prolong the coherence times of quantum systems under noisy environments. Uhrig's dynamical decoupling scheme provides an optimal sequence for a quantum system interacting with a dephasing…

Quantum Physics · Physics 2011-10-10 Soumya Singha Roy , T. S. Mahesh , G. S. Agarwal

The fundamental assumption of dynamical decoupling based noise spectroscopy is that the coherence decay rate of qubit (or qubits) driven with a sequence of many pulses, is well approximated by the environmental noise spectrum spanned on…

Mesoscale and Nanoscale Physics · Physics 2018-03-13 Piotr Szańkowski , Łukasz Cywiński