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A computational problem fed into a gate-model quantum computer identifies an objective function with a particular computational pathway (objective function connectivity). The solution of the computational problem involves identifying a…

Quantum Physics · Physics 2020-03-12 Laszlo Gyongyosi

Quantum systems can be exquisite sensors thanks to their sensitivity to external perturbations. This same characteristic also makes them fragile to external noise. Quantum control can tackle the challenge of protecting quantum sensors from…

Quantum Physics · Physics 2018-06-13 F. Poggiali , P. Cappellaro , N. Fabbri

The optimal quantum control theory is employed to determine electric pulses capable of producing quantum gates with high fidelity (higher than 0.9997). Particularly, these quantum gates were chosen to perform the permutation algorithm (Z.…

Quantum Physics · Physics 2018-03-28 C. M. Rivera-Ruiz , E. F. de Lima , F. F. Fanchini , V. Lopez-Richard , L. K. Castelano

We consider the problem of carrying an initial Bloch vector to a final Bloch vector in a specified amount of time under the action of three control fields (a vector control field). We show that this control problem is solvable and therefore…

Quantum Physics · Physics 2012-02-21 K. M. Fonseca-Romero , G. Useche-Laverde , F. Torres-Ardila

We consider the implementation of a unitary gate on a qubit system S via a global energy-preserving operation acting on S and an auxiliary system B that can be seen as a battery. We derive a simple, asymptotically exact expression for the…

This paper presents a quantum approach for the formulation and solution of the prosumer problem, i.e., the problem of minimizing the energy cost incurred by a number of users in an energy community, while addressing the constraints given by…

Quantum Physics · Physics 2023-02-01 Carlo Mastroianni , Luigi Scarcello , Jacopo Settino

Quantum technologies are developing powerful tools to generate and manipulate coherent superpositions of different energy levels. Envisaging a new generation of energy-efficient quantum devices, here we explore how coherence can be…

Quantum Physics · Physics 2017-09-06 Giulio Chiribella , Yuxiang Yang

The aim of this work is to study the physical properties of a one-way quantum computer in an effective low-energy cluster state. We calculate the optimal working conditions as a function of the temperature and of the system parameters. The…

Quantum Physics · Physics 2011-11-28 D. Klagges , K. P. Schmidt

Quantum computation using electron spins in three coupled dot with different size is proposed. By using the energy selectivity of both photon assisted tunneling and spin rotation of electrons, logic gates are realized by static and…

Quantum Physics · Physics 2007-05-23 H. Sasakura , S. Muto

Adiabatic state engineering is a powerful technique in quantum information and quantum control. However, its performance is limited by the adiabatic theorem of quantum mechanics. In this scenario, shortcuts to adiabaticity, such as provided…

Quantum Physics · Physics 2015-11-03 Alan C. Santos , Marcelo S. Sarandy

Universal quantum computation using optical coherent states is studied. A teleportation scheme for a coherent-state qubit is developed and applied to gate operations. This scheme is shown to be robust to detection inefficiency.

Quantum Physics · Physics 2009-11-07 H. Jeong , M. S. Kim

We employ optimal control theory to design optimized quantum gates for solid-state qubits subject to decoherence. At the example of a gate-controlled semiconductor quantum dot molecule we demonstrate that decoherence due to phonon couplings…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Ulrich Hohenester

Innovative solutions and developments are being inspected to tackle rising electrical power demand to be supplied by clean forms of energy. The integration of renewable energy generations, varying nature loads, importance of active role of…

Simple, precise, and robust control is demanded for operating a large quantum information processor. However, existing routes to high-fidelity quantum control rely heavily on arbitrary waveform generators that are difficult to scale up.…

Quantum Physics · Physics 2022-09-21 Qi-Ming Chen , Herschel Rabitz , Re-Bing Wu

A limited number of qubits, high error rates, and limited qubit connectivity are major challenges for effective near-term quantum computations. Quantum circuit partitioning divides a quantum computation into a set of computations that…

Quantum Physics · Physics 2023-08-21 Sebastian Brandhofer , Ilia Polian , Kevin Krsulich

Universal set of quantum gates are realized from the conduction-band electron spin qubits of quantum dots embedded in a microcavity via two-channel Raman interaction. All of the gate operations are independent of the cavity mode states,…

Quantum Physics · Physics 2007-12-20 Ping Dong , Ming Yang , Zhuo-Liang Cao

Coherent carrier control in quantum nanostructures is studied within the framework of Optimal Control. We develop a general solution scheme for the optimization of an external control (e.g., lasers pulses), which allows to channel the…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 Alfio Borzi , Georg Stadler , Ulrich Hohenester

As quantum computing resources remain scarce and error rates high, minimizing the resource consumption of quantum circuits is essential for achieving practical quantum advantage. Here we consider the natural problem of, given a circuit $C$,…

Quantum Physics · Physics 2026-02-27 Adam Husted Kjelstrøm , Andreas Pavlogiannis , Jaco van de Pol

Using electrostatic gates to control the electron positions, we present a new controlled-NOT gate based on quantum dots. The qubit states are chosen to be the spin states of an excess conductor electron in the quantum dot; and the main…

Quantum Physics · Physics 2007-05-23 Cyrus C. Y. Lin , Chopin Soo , Yin-Zhong Wu , Wei-Min Zhang

The question of how fast a quantum state can evolve has attracted a considerable attention in connection with quantum measurement, metrology, and information processing. Since only orthogonal states can be unambiguously distinguished, a…

Quantum Physics · Physics 2015-05-13 Lev B. Levitin , Tommaso Toffoli