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We examine how the interference of a coherent light-pulse with its slightly time-delayed copy may generate a pulse nearly identical to the original one and ahead of it. The simplicity of this 2-pulse system enabled us to obtain exact…

Optics · Physics 2016-08-14 Bruno Macke , Bernard Ségard

Quantum information processing requires overcoming decoherence---the loss of "quantumness" due to the inevitable interaction between the quantum system and its environment. One approach towards a solution is quantum dynamical decoupling---a…

Quantum Physics · Physics 2011-07-26 Xinhua Peng , Dieter Suter , Daniel A. Lidar

We employ a quantum master equations approach based on a vectorial Maxwell-pseudospin model to compute the quantum evolution of the spin populations and coherences in the fundamental singlet trion transition of a negatively charged quantum…

Mesoscale and Nanoscale Physics · Physics 2019-04-03 G. Slavcheva , M. Koleva , A. Rastelli

We present a new method for determining pulse imperfections and improving the single-gate fidelity in a superconducting qubit. By applying consecutive positive and negative $\pi$ pulses, we amplify the qubit evolution due to microwave pulse…

Signals comprised of a stream of short pulses appear in many applications including bio-imaging and radar. The recent finite rate of innovation framework, has paved the way to low rate sampling of such pulses by noticing that only a small…

Information Theory · Computer Science 2015-05-18 Ronen Tur , Yonina C. Eldar , Zvi Friedman

We present an iterative method to solve the multipartite quantum state estimation problem. We demonstrate convergence for any informationally complete set of generalized quantum measurements in every finite dimension. Our method exhibits…

Quantum Physics · Physics 2022-03-21 Daniel Uzcategui Contreras , Gabriel Senno , Dardo Goyeneche

We design composite controlled-phase gates, which compensate errors in the phase of a single gate. The errors can be of various nature, such as relative, absolute or both. We present composite sequences which are robust to relative errors…

Quantum Physics · Physics 2015-09-02 Svetoslav S. Ivanov , Nikolay V. Vitanov

How to achieve an arbitrary real-valued probability amplitude in the general single-partite or multipartite quantum system without measuring any other quantum state's probability amplitude? How to achieve an arbitrary real-valued…

Quantum Physics · Physics 2020-09-01 Xu Guanlei

Preparation of quantum state lies at the heart of quantum information processing. The greedy algorithm provides a potential method to effectively prepare quantum states. However, the standard greedy algorithm, in general, cannot take the…

Quantum Physics · Physics 2022-07-12 Run-Hong He , Hai-Da Liu , Sheng-Bin Wang , Jing Wu , Shen-Shuang Nie , Zhao-Ming Wang

Using nuclear magnetic resonance techniques, we experimentally investigated the effects of applying a two bit phase error detection code to preserve quantum information in nuclear spin systems. Input states were stored with and without…

We present and implement a new scheme for independent control of both the final and the transient population utilizing the symmetry properties of the system. By proper pulse shaping, utilizing the invariance of the two-photon absorption to…

Atomic Physics · Physics 2009-10-20 Andrey Gandman , Leonid Rybak , Michal Bronstein , Naser Shakour , Zohar Amitay

The pulse control of decoherence in a qubit interacting with a quantum environment is studied with focus on a general case where decoherence is induced by both pure dephasing and population decay. To observe how the decoherence is…

Quantum Physics · Physics 2009-11-11 Takahiro Murakami , Yositake Takane

We design realizable time-dependent semiclassical pulses to invert the population of a two-level system faster than adiabatically when the rotating-wave approximation cannot be applied. Different approaches, based on the counterdiabatic…

Quantum Physics · Physics 2016-01-06 S. Ibáñez , Yi-Chao Li , Xi Chen , J. G. Muga

We generalize the problem of the coherent control of small quantum systems to the case where the quantum bit (qubit) is subject to a fully general rotation. Following the ideas developed in Pasini et al (2008 Phys. Rev. A 77, 032315), the…

Quantum Physics · Physics 2008-07-09 S. Pasini , G. S. Uhrig

Dynamical error suppression techniques are commonly used to improve coherence in quantum systems. They reduce dephasing errors by applying control pulses designed to reverse erroneous coherent evolution driven by environmental noise.…

We present a detailed analysis of coherence creation in a four level double lambda-like atomic system using a train of ultra-short few-cycle Gaussian pulses. The effect of the Doppler broadening has been analyzed. It is possible to create…

Quantum Physics · Physics 2015-06-22 Amarendra K. Sarma , Pawan Kumar

In general, a quantum measurement yields an undetermined answer and alters the system to be consistent with the measurement result. This process maps multiple initial states into a single state and thus cannot be reversed. This has…

We give several algorithms for reconstructing quantum states of swift electrons, using maximum likelihood estimation, Bayesian inversion, and deep learning. We apply these algorithms to data previously recorded for an attosecond electron…

Quantum Physics · Physics 2025-08-26 Hao Jeng , Claus Ropers

It is shown theoretically that the use of accelerating spatiotemporal quasi-phase-matching (QPM) modulation patterns in media with parametric optical interactions makes it possible to generate a time-reversed replica of the pump pulse…

Optics · Physics 2016-10-17 Michal Yachini , Boris Malomed , Alon Bahabad

Qudits, generalizations of qubits to multi-level quantum systems, offer enhanced computational efficiency by encoding more information per lattice cell, avoiding costly swap operations and providing even exponential speedup in some cases.…

Quantum Physics · Physics 2025-10-09 Boxi Li , F. A. Cárdenas-López , Adrian Lupascu , Felix Motzoi