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Reading a qubit is a fundamental operation in quantum computing. It translates quantum information into classical information enabling subsequent classification to assign the qubit states `0' or `1'. Unfortunately, qubit readout is one of…

Using two trapped ion species ($\rm{^{27}Al^+}$ and $\rm{^9Be^+}$) as primary and ancillary systems, we implement qubit measurements based on the repetitive transfer of information and quantum nondemolition detection. The repetition…

Quantum Physics · Physics 2007-05-23 D. B. Hume , T. Rosenband , D. J. Wineland

We theoretically study the quantum speed limit of a single atom trapped in a Fabry-Perot microresonator. The cavity mode will be squeezed when a driving laser is applied to the second-order nonlinear medium, and the effective Hamiltonian…

Quantum Physics · Physics 2023-10-25 Ya-Jie Ma , Xue-Chen Gao , Shao-Xiong Wu , Chang-shui Yu

Measuring a qubit state is a fundamental yet error-prone operation in quantum computing. These errors can arise from various sources, such as crosstalk, spontaneous state transitions, and excitations caused by the readout pulse. Here, we…

Multi-time-scale stochastic approximation is an iterative algorithm for finding the fixed point of a set of $N$ coupled operators given their noisy samples. It has been observed that due to the coupling between the decision variables and…

Optimization and Control · Mathematics 2024-09-13 Sihan Zeng , Thinh T. Doan

The emergence of artificial intelligence (AI) accelerators like NVIDIA Tensor Cores offers new opportunities to speed up tensor-heavy scientific computations. However, applying them to quantum chemistry is challenging due to strict accuracy…

Chemical Physics · Physics 2026-04-20 Hua Huang , Wenkai Shao , Jeff Hammond

Phase estimation with potentially large phase values, i.e., with large dynamic range, has many applications in quantum metrology, for example to atomic clocks. A recently proposed phase estimation scheme approaches the Heisenberg scaling in…

Quantum Physics · Physics 2026-03-17 Tyler G. Thurtell , Akimasa Miyake

Single-shot fidelity is the standard benchmark for superconducting qubit readout, yet it does not directly minimize the wall-clock time needed to certify a quantum state. We treat the dispersive measurement record as a stochastic…

Quantum Physics · Physics 2026-03-11 Sinan Bugu

We analyze three different post-processing methods applied to a single-shot qubit readout: the average-signal (boxcar filter), peak-signal, and maximum-likelihood methods. In contrast to previous work, we account for a stochastic turn-on…

Quantum Physics · Physics 2014-01-16 B. D'Anjou , W. A. Coish

Machine learning employs dynamical algorithms that mimic the human capacity to learn, where the reinforcement learning ones are among the most similar to humans in this respect. On the other hand, adaptability is an essential aspect to…

Quantum Physics · Physics 2018-10-15 F. Albarrán-Arriagada , J. C. Retamal , E. Solano , L. Lamata

Qubit measurements in quantum devices involve various types of errors, including erroneous state determination, correlated preparation errors and measurement-induced leakage from the computational states. We propose a feedforward protocol…

Quantum Physics · Physics 2025-12-03 Liran Shirizly , Dekel Meirom , Malcolm Carroll , Haggai Landa

In semiconductor spin quantum bits (qubits), the radio-frequency (RF) gate-based readout is a promising solution for future large-scale integration, as it allows for a fast, frequency-multiplexed readout architecture, enabling multiple…

In semiconductor nanostructures, spin blockade (SB) is the most scalable mechanism for electrical spin readout, requiring only two bound spins for its implementation. In conjunction with charge sensing techniques, SB has led to…

Fastness and robustness are both critical in the implementation of high-fidelity gates for quantum computation, but in practice, a trade-off has to be made between them. In this paper, we investigate the underlying robust time-optimal…

Quantum Physics · Physics 2023-09-12 Xi Cao , Jiangyu Cui , Man Hong Yung , Re-Bing Wu

In certain regimes, the fidelity of quantum states will decay at a rate set by the classical Lyapunov exponent. This serves both as one of the most important examples of the quantum-classical correspondence principle and as an accurate test…

Quantum Physics · Physics 2022-09-14 Max D. Porter , Ilon Joseph

Squeezing transformation as an essential component, gives rise to the possibility to perform various tasks of quantum information processing. However, the reported squeezing gate with best performance so far is a conditional realization at…

Quantum Physics · Physics 2022-02-16 Xiaocong Sun , Yajun Wang , Yuhang Tian , Qingwei Wang , Long Tian , Yaohui Zheng , Kunchi Peng

We describe how to perform fast quantum limited read-out of a solid state qubit biased at its degeneracy point. The method is based on homodyne detection of the phase of a microwave signal reflected by a slow oscillator coupled to the…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 G. Johansson , L. Tornberg , C. M. Wilson

Increasing quantum circuit fidelity requires an efficient instruction set to avoid errors from decoherence. The choice of a two-qubit (2Q) hardware basis gate depends on a quantum modulator's native Hamiltonian interactions and applied…

Quantum Physics · Physics 2025-04-22 Evan McKinney , Chao Zhou , Mingkang Xia , Michael Hatridge , Alex K. Jones

Recall the classical hypothesis testing setting with two convex sets of probability distributions P and Q. One receives either n i.i.d. samples from a distribution p in P or from a distribution q in Q and wants to decide from which set the…

Information Theory · Computer Science 2020-07-20 Fernando G. S. L. Brandao , Aram W. Harrow , James R. Lee , Yuval Peres

In this brief, we set up the finite time stability (FnTSta) theory for dynamical systems with bounded time-varying delays via aperiodically intermittent control (AIC) and quantized control (QC). A more general QC is designed in this brief.…

Systems and Control · Electrical Eng. & Systems 2020-02-21 Xiwei Liu , Hailian Ma