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One of the main enablers in quantum computing is having qubit control that is precise and fast. However, qubits typically have multilevel structures making them prone to unwanted transitions from fast gates. This leakage out of the…

With gate error rates in multiple technologies now below the threshold required for fault-tolerant quantum computation, the major remaining obstacle to useful quantum computation is scaling, a challenge greatly amplified by the huge…

Quantum Physics · Physics 2021-12-09 Kianna Wan , Soonwon Choi , Isaac H. Kim , Noah Shutty , Patrick Hayden

Leakage errors occur when a quantum system leaves the two-level qubit subspace. Reducing these errors is critically important for quantum error correction to be viable. To quantify leakage errors, we use randomized benchmarking in…

Quantum computation can be performed by encoding logical qubits into the states of two or more physical qubits, and controlling a single effective exchange interaction and possibly a global magnetic field. This "encoded universality"…

Quantum Physics · Physics 2007-05-23 M. Mohseni , D. A. Lidar

Working with trapped atoms at close distance to each other, we show that one can implement entangling gates based on non-independent qubits using a single pulse per qubit, or a single structured pulse. The optimal parameters depend on…

Quantum Physics · Physics 2023-10-19 Ignacio R. Sola , Seokmin Shin , Bo Y. Chang

Motivated by recent realizations of qubits with a readout by macroscopic quantum tunneling in a Josephson junction, we study the problem of barrier penetration in presence of coupling to a spin-${1\over 2}$ system. It is shown that when the…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 Joachim Ankerhold , Hermann Grabert

Quantum error correction (QEC) is one of the crucial building blocks for developing quantum computers that have significant potential for reaching a quantum advantage in applications. Prominent candidates for QEC are stabilizer codes for…

A common approach to realize conditional-phase (CZ) gates in transmon qubits relies on flux control of the qubit frequency to make computational states interact with non-computational ones using a fast-adiabatic trajectory to minimize…

Fault-tolerant quantum computation using two-dimensional topological quantum error correcting codes can benefit from multi-qubit long-range operations. By using simple commutation rules, a quantum circuit can be transpiled into a sequence…

We present a set of experimentally feasible pulse sequences that implement any single-qubit gate on a singlet-triplet spin qubit and demonstrate that these new sequences are up to three times faster than existing sequences in the…

Mesoscale and Nanoscale Physics · Physics 2017-11-22 Robert E. Throckmorton , Chengxian Zhang , Xu-Chen Yang , Xin Wang , Edwin Barnes , S. Das Sarma

The fault-tolerant operation of logical qubits is an important requirement for realizing a universal quantum computer. Spin qubits based on quantum dots have great potential to be scaled to large numbers because of their compatibility with…

Single flux quantum pulses are a natural candidate for on-chip control of superconducting qubits. We show that they can drive high-fidelity single-qubit rotations---even in leaky transmon qubits---if the pulse sequence is suitably…

Quantum Physics · Physics 2016-09-07 Per J. Liebermann , Frank K. Wilhelm

We develop a systematic method of performing corrected gate operations on an array of exchange-coupled singlet-triplet qubits in the presence of both fluctuating nuclear Overhauser field gradients and charge noise. The single-qubit control…

Quantum Physics · Physics 2013-04-12 J. P. Kestner , Xin Wang , Lev S. Bishop , Edwin Barnes , S. Das Sarma

We propose a modified quantum annealing protocol, i. e., pulsed quantum annealing} (PQA), in order to increase the success probability by a pulse application during the quantum annealing process. It is well known that the success…

Quantum Physics · Physics 2020-08-18 Vasilios Karanikolas , Shiro Kawabata

We consider the transition of electron between two quantum dots in which the discrete levels are swept past each other with a constant velocity. If a direct tunneling between the dot levels was allowed, an electron will be transferred…

Mesoscale and Nanoscale Physics · Physics 2022-08-17 M. E. Raikh

We demonstrate a simple pulse shaping technique designed to improve the fidelity of spin-dependent force operations commonly used to implement entangling gates in trapped-ion systems. This extension of the M{\o}lmer-S{\o}rensen gate can…

Quantum Physics · Physics 2013-05-30 D. Hayes , S. M. Clark , S. Debnath , D. Hucul , I. V. Inlek , K. W. Lee , Q. Quraishi , C. Monroe

Accurate and efficient implementation of parallel quantum gates is crucial for scalable quantum information processing. However, the unavoidable crosstalk between qubits in current noisy processors impedes the achievement of high gate…

Quantum Physics · Physics 2026-01-06 Xiaodong Yang , Ran Liu , Jun Li

We derive a set of composite pulse sequences that generates CNOT gates and correct all systematic errors within the logical subspace to arbitrary order. These sequences are applicable for any two-qubit interaction Hamiltonian, and make no…

Quantum Physics · Physics 2017-04-19 Fernando A. Calderon-Vargas , J. P. Kestner

We propose a simple method for realizing a multiqubit phase gate of one qubit simultaneously controlling $n$ target qubits, by using three-level quantum systems (i.e., qutrits) coupled to a cavity or resonator. The gate can be implemented…

Quantum Physics · Physics 2015-06-19 Chui-Ping Yang , Qi-Ping Su , Feng-Yang Zhang , Shi-Biao Zheng

We simulate the implementation of a T-gate, or $\frac{\pi}{8}$-gate, for a [7,1,3] encoded logical qubit in a non-equiprobable error environment. We demonstrate that the use of certain non-fault tolerant methods in the implementation may…

Quantum Physics · Physics 2015-06-15 Yaakov S. Weinstein