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High-fidelity entangling gates are essential for quantum computation. Currently, most approaches to designing such gates are based either on simple, analytical pulse waveforms or on ones obtained from numerical optimization techniques. In…

Quantum Physics · Physics 2023-09-15 Ho Lun Tang , Kyle Connelly , Ada Warren , Fei Zhuang , Sophia E. Economou , Edwin Barnes

Multi-qubit entangling interactions arise naturally in several quantum computing platforms and promise advantages over traditional two-qubit gates. In particular, a fixed multi-qubit Ising-type interaction together with single-qubit X-gates…

Quantum Physics · Physics 2024-03-13 Pascal Baßler , Markus Heinrich , Martin Kliesch

A universal set of quantum gates is constructed for the recently developed jump-error correcting quantum codes. These quantum codes are capable of correcting errors arising from the spontaneous decay of distinguishable qubits into…

Quantum Physics · Physics 2007-05-23 G. Alber , M. Mussinger , A. Delgado

Any unitary operation in quantum information processing can be implemented via a sequence of simpler steps - quantum gates. However, actual implementation of a quantum gate is always imperfect and takes a finite time. Therefore, seeking for…

Quantum Physics · Physics 2009-09-29 Michal Sedlak , Martin Plesch

Quantum computing tries to exploit entanglement and interference to process information more efficiently than the best known classical solutions. Experiments demonstrating the feasibility of this approach have already been performed.…

Other Condensed Matter · Physics 2008-01-08 Almut Beige

Quantum simulation traditionally relies on unitary dynamics, inherently imposing efficiency constraints on the generation of intricate entangled states. In principle, these limitations can be superseded by non-unitary, dynamic circuits.…

The prevalent approach to executing quantum algorithms on quantum computers is to break-down the algorithms to a concatenation of universal gates, typically single and two-qubit gates. However such a decomposition results in long gate…

Quantum Physics · Physics 2020-03-25 Yotam Shapira , Ravid Shaniv , Tom Manovitz , Nitzan Akerman , Lee Peleg , Lior Gazit , Roee Ozeri , Ady Stern

Superconducting quantum circuit is a promising system for building quantum computer. With this system we demonstrate the universal quantum computations, including the preparing of initial states, the single-qubit operations, the two-qubit…

Quantum Physics · Physics 2018-09-06 Nian-Quan Jiang , Yao Chen , Chuanbing Cai , Ming-FengWang , Junwang Tang

A single physical interaction might not be universal for quantum computation in general. It has been shown, however, that in some cases it can generate universal quantum computation over a subspace. For example, by encoding logical qubits…

Quantum Physics · Physics 2007-05-23 M. Hsieh , J. Kempe , S. Myrgren , K. B. Whaley

We propose a new implementation of a universal set of one- and two-qubit gates for quantum computation using the spin states of coupled single-electron quantum dots. Desired operations are effected by the gating of the tunneling barrier…

Mesoscale and Nanoscale Physics · Physics 2009-10-30 Daniel Loss , David P. DiVincenzo

Quantum processors which combine the long decoherence times of spin qubits together with fast optical manipulation of excitons have recently been the subject of several proposals. I show here that arbitrary single- and entangling two-qubit…

Quantum Physics · Physics 2007-05-23 Brendon W. Lovett

I describe the use of techniques based on composite rotations to combat systematic errors in controlled phase gates, which form the basis of two qubit quantum logic gates. Although developed and described within the context of Nuclear…

Quantum Physics · Physics 2007-05-23 Jonathan A. Jones

We demonstrate that conditional as well as unconditional basic operations which are prerequisite for universal quantum gates can be performed with almost 100% fidelity within a strongly interacting two-electron quantum ring. Both sets of…

Mesoscale and Nanoscale Physics · Physics 2016-08-14 Lene Sælen , Erik Waltersson , J. P. Hansen , Eva Lindroth

Quantum logic gates can perform calculations much more efficiently than their classical counterparts. However, the level of control needed to obtain a reliable quantum operation is correspondingly higher. In order to evaluate the…

Quantum Physics · Physics 2009-11-13 Holger F. Hofmann , Ryo Okamoto , Shigeki Takeuchi

Optimal control theory is a powerful tool for improving figures of merit in quantum information tasks. Finding the solution to any optimal control problem via numerical optimization depends crucially on the choice of the optimization…

Unlike fixed designs, programmable circuit designs support an infinite number of operators. The functionality of a programmable circuit can be altered by simply changing the angle values of the rotation gates in the circuit. Here, we…

Quantum Physics · Physics 2012-12-27 Anmer Daskin , Ananth Grama , Giorgos Kollias , Sabre Kais

It is known that it is possible to encode a logical qubit over many physical qubits such that it is immune to the effects of collective decoherence, and it is possible to perform universal quantum computation using these `decoherence-free'…

Quantum Physics · Physics 2013-10-30 Bobby Antonio , Sougato Bose

Universal quantum entangling gates are a crucial building block in the large-scale quantum computation and quantum communication, and it is an important task to find simple ways to implement them. Here an effective quantum circuit for the…

Quantum Physics · Physics 2022-03-31 Wen-Qiang Liu , Hai-Rui Wei , Leong-Chuan Kwek

We investigate the potential of bio-inspired evolutionary algorithms for designing quantum circuits with specific goals, focusing on two particular tasks. The first one is motivated by the ideas of Artificial Life that are used to reproduce…

Quantum Physics · Physics 2025-10-02 Shailendra Bhandari , Stefano Nichele , Sergiy Denysov , Pedro G. Lind

Unitary gates with high entangling capabilities are relevant for several quantum-enhanced technologies. For symmetric multiqubit systems, such as spin states or bosonic systems, the particle exchange symmetry restricts these gates and also…