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For a generic dynamical decoupling sequence employing a single-axis control, we study its efficiency in the presence of small errors in direction of the controlling-pulses. In the case that the corresponding ideal dynamical-decoupling…

Quantum Physics · Physics 2013-05-29 Zhihao Xiao , Lewei He , Wen-ge Wang

One of the main requirements to achieve reliable quantum communications are on-demand sources of highly entangled photon pairs, and semiconductor quantum dots have emerged as prominent candidates to satisfy the necessary conditions of…

In the scaling development of quantum computers, the calibration process emerges as a critical challenge. Existing calibration methods, utilizing the same pulse waveform for two-qubit gates across the device, overlook hardware differences…

Quantum Physics · Physics 2024-12-02 Yuchen Zhu , Jinglei Cheng , Boxi Li , Yidong Zhou , Yufei Ding , Zhiding Liang

Power broadening $-$ the broadening of the spectral line profile of a two-state quantum transition as the amplitude of the driving field increases $-$ is a well-known and thoroughly examined phenomenon in spectroscopy. It typically occurs…

Quantum Physics · Physics 2025-10-21 Ivo S. Mihov , Nikolay V. Vitanov

PulsePol is an elegantly designed pulse-sequence-based quantum control scheme that enables polarization transfer between electron and nuclear spins, for example, in nitrogen-vacancy (NV) centers. However, previous analyses of PulsePol…

A method for measuring small energy level shifts in a qubit by coherent amplification of their effect is proposed. It is based on the repeated application of the same interaction pulse in two manners: with the same phase of each subsequent…

Quantum Physics · Physics 2021-06-16 Nikolay V. Vitanov

In an earlier paper (Ahuja, et al, 2005), based on simultaneous multi-frequency observations with the Giant Metrewave Radio Telescope (GMRT), we reported the variation of pulsar dispersion measures (DMs) with frequency. A few different…

Astrophysics · Physics 2008-11-26 Amrit Lal Ahuja , Dipanjan Mitra , Yashwant Gupta

We present a formulation for investigating quench dynamics across quantum phase transitions in the presence of decoherence. We formulate decoherent dynamics induced by continuous quantum non-demolition measurements of the instantaneous…

Quantum Physics · Physics 2021-03-16 Wei-Ting Kuo , Daniel Arovas , Smitha Vishveshwara , Yi-Zhuang You

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

We investigate the quantum phase transition (QPT) in the XXZ central spin model, which can be described as a spin-1/2 particle coupled to N bath spins. In general, the QPT is supposed to occur only in the thermodynamical limit. In contrast,…

Quantum Physics · Physics 2023-02-01 Lei Shao , Rui Zhang , Wangjun Lu , Zhucheng Zhang , Xiaoguang Wang

Using numerical calculations, we compare the collective transition probabilities of many spins in random magnetic fields, subject to either frequent projective measurements, frequent phase modulations, or a mix of modulations and…

Quantum Physics · Physics 2014-08-04 Wenxian Zhang , A. G. Kofman , Jun Zhuang , J. Q. You , Franco Nori

A dynamical quantum phase transition can occur during time evolution of sudden quenched quantum systems across a phase transition. It corresponds to the nonanalytic behavior at a critical time of the rate function of the quantum state…

Quantum Physics · Physics 2019-05-14 Xue-Yi Guo , Chao Yang , Yu Zeng , Yi Peng , He-Kang Li , Hui Deng , Yi-Rong Jin , Shu Chen , Dongning Zheng , Heng Fan

Quantum phase transitions (QPTs) in odd-mass Nb isotopes are investigated in the framework of the interacting boson-fermion model with configuration mixing. A quantum analysis reveals a Type I QPT (gradual shape-evolution within the…

Nuclear Theory · Physics 2025-11-27 A. Leviatan

Relaxation effects impose fundamental limitations on our ability to coherently control quantum mechanical phenomena. In this letter, we establish physical limits on how closely can a quantum mechanical system be steered to a desired target…

Quantum Physics · Physics 2009-11-10 N. Khaneja , B. Luy , S. J. Glaser

Analog quantum simulators can directly emulate time-dependent Hamiltonian dynamics, enabling the exploration of diverse physical phenomena such as phase transitions, quench dynamics, and non-equilibrium processes. Realizing accurate analog…

Quantum Physics · Physics 2025-12-04 Yulong Dong , Christopher Kang , Murphy Yuezhen Niu

Achieving precise control over quantum systems presents a significant challenge, especially in many-body setups, where residual couplings and unintended transitions undermine the accuracy of quantum operations. In superconducting qubits,…

We propose a methodology to design optimal pulses for achieving quantum optimal control on molecular systems. Our approach constrains pulse shapes to linear combinations of a fixed number of experimentally relevant pulse functions. Quantum…

Quantum Physics · Physics 2015-10-28 Ruben D. Guerrero , Carlos A. Arango , Andres Reyes

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 present pulse sequences for two-qubit gates acting on encoded qubits for exchange-only quantum computation. Previous work finding such sequences has always required numerical methods due to the large search space of unitary operators…

Quantum Physics · Physics 2014-07-23 Daniel Zeuch , R. Cipri , N. E. Bonesteel

Pulse-shape discrimination (PSD) is usually achieved using the different fast and slow decay components of inorganic scintillators, such as BaF2, CsI:Tl, etc. However, LaBr3:Ce is considered to not possess different components at room…

Instrumentation and Detectors · Physics 2021-09-03 Jirong Cang , XinChao Fang , Zhi Zeng , Ming Zeng , Yinong Liu , Zhigang Sun , Ziyun Chen