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Because of their long coherence time and compatibility with industrial foundry processes, electron spin qubits are a promising platform for scalable quantum processors. A full-fledged quantum computer will need quantum error correction,…

Growth in the complexity and capabilities of quantum information hardware mandates access to practical techniques for performance verification that function under realistic laboratory conditions. Here we experimentally characterise the…

Quantum Physics · Physics 2019-07-02 S. Mavadia , C. L. Edmunds , C. Hempel , H. Ball , F. Roy , T. M. Stace , M. J. Biercuk

We demonstrate complete characterization of a two-qubit entangling process - a linear optics controlled-NOT gate operating with coincident detection - by quantum process tomography. We use maximum-likelihood estimation to convert the…

Quantum Physics · Physics 2008-11-26 J. L. O'Brien , G. J. Pryde , A. Gilchrist , D. F. V. James , N. K. Langford , T. C. Ralph , A. G. White

Following a key idea of unconventional geometric quantum computation developed earlier [Phys. Rev. Lett. 91, 197902 (2003)], here we propose a more general scheme in such an intriguing way: $\gamma_{d}=\alpha_{g}+\eta \gamma _{g}$, where…

Quantum Physics · Physics 2009-11-11 J. Du , P. Zou , Z. D. Wang

Characterization of quantum states is a fundamental requirement in quantum science and technology. As a promising framework, shadow tomography shows significant efficiency in estimating linear functions, however, for the challenging…

Quantum Physics · Physics 2024-04-19 Xu-Jie Peng , Qing Liu , Lu Liu , Ting Zhang , You Zhou , He Lu

Raman qubits, represented by two ground or metastable quantum states coupled via an intermediate state, hold some advantages over directly coupled qubits, most notably much longer radiative lifetimes, shorter gate duration and lower…

Quantum Physics · Physics 2023-10-09 Stancho G. Stanchev , Nikolay V. Vitanov

The experimental implementation of selective quantum process tomography (SQPT) involves computing individual elements of the process matrix with the help of a special set of states called quantum 2-design states. However, the number of…

Quantum Physics · Physics 2022-07-12 Akshay Gaikwad , Krishna Shende , Arvind , Kavita Dorai

While all quantum algorithms can be expressed in terms of single-qubit and two-qubit gates, more expressive gate sets can help reduce the algorithmic depth. This is important in the presence of gate errors, especially those due to…

To guarantee the normal functioning of quantum devices in different scenarios, appropriate benchmarking tool kits are quite significant. Inspired by the recent progress on quantum state verification, here we establish a general framework of…

Quantum Physics · Physics 2020-07-01 Pei Zeng , You Zhou , Zhenhuan Liu

Most near-term quantum information processing devices will not be capable of implementing quantum error correction and the associated logical quantum gate set. Instead, quantum circuits will be implemented directly using the physical native…

Among the cost metrics characterizing a quantum circuit, the $T$-count stands out as one of the most crucial as its minimization is particularly important in various areas of quantum computation such as fault-tolerant quantum computing and…

Quantum Physics · Physics 2025-09-17 Vivien Vandaele

In this paper, we develop a new classical simulation of quantum bit (qubit) by use of analog components in order to be able to simulate the quantum properties such as the superposition of states. As part of this new approach, we have also…

Quantum Physics · Physics 2020-05-27 A. Chouikh , T. Said , M. Bennai

High-fidelity two-qubit gates are essential for scalable quantum computing. We present a scheme based on superconducting transmon qubits and a control pulse delivery protocol that enables arbitrary controlled-phase gates modulated solely by…

We have implemented a Walsh-Hadamard gate, which performs a quantum Fourier transform, in a superconducting qutrit. The qutrit is encoded in the lowest three energy levels of a capacitively shunted flux device, operated at the optimal…

Quantum Physics · Physics 2020-11-17 M. A. Yurtalan , J. Shi , M. Kononenko , A. Lupascu , S. Ashhab

Processing quantum information using quantum three-level systems or qutrits as the fundamental unit is an alternative to contemporary qubit-based architectures with the potential to provide significant computational advantages. We…

Quantum Physics · Physics 2022-11-15 Tanay Roy , Ziqian Li , Eliot Kapit , David I. Schuster

Dissipative cat qubits are a promising physical platform for quantum computing, since their large noise bias can enable more hardware-efficient quantum error correction. In this work we theoretically study the long-term prospects of a…

Scaling up quantum computing hardware is hindered by the narrow operating margins of current quantum components. Here, we introduce a composite qubit and gate scheme that achieves wide margins by use of transistor-like nonlinearities to…

Quantum Physics · Physics 2022-02-23 Ryan J. Epstein

The state vector-based simulation offers a convenient approach to developing and validating quantum algorithms with noise-free results. However, limited by the absence of cache-aware implementations and unpolished circuit optimizations, the…

Quantum Physics · Physics 2024-06-21 Chuan-Chi Wang , Yu-Cheng Lin , Yan-Jie Wang , Chia-Heng Tu , Shih-Hao Hung

The efficient certification of classically intractable quantum devices has been a central research question for some time. However, to observe a "quantum advantage", it is believed that one does not need to build a large scale universal…

Quantum Physics · Physics 2018-03-05 Daniel Mills , Anna Pappa , Theodoros Kapourniotis , Elham Kashefi

We introduce a novel quantum control method for superconducting transmon qubits that substantially outperforms conventional techniques in precision and robustness against coherent errors. Our approach leverages composite pulses (CP) to…

Quantum Physics · Physics 2025-06-10 Hristo G. Tonchev , Boyan T. Torosov , Nikolay V. Vitanov