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It is shown that classical control diagrams can be mapped one-to-one onto quantum path integrals over measurement amplitudes. To show the practical utility of this method, exact closed-form expressions are derived for the control dynamics…

Quantum Physics · Physics 2007-05-23 J. A. Sidles

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

The kinematics of many nonlinear control systems, especially in the robotics field, admit a transitive Lie-group symmetry, which is useful in high performance observer design. The recently proposed equivariant filter (EqF) exploits…

Systems and Control · Electrical Eng. & Systems 2022-09-13 Yixiao Ge , Pieter van Goor , Robert Mahony

Quantum Fourier transform (QFT) is a key function to realize quantum computers. A QFT followed by measurement was demonstrated on a simple circuit based on fiber-optics. The QFT was shown to be robust against imperfections in the rotation…

Quantum Physics · Physics 2007-05-23 Akihisa Tomita , Kazuo Nakamura

Quantum Fourier transform (QFT) is a widely used building block for quantum algorithms, whose scalable implementation is challenging in experiments. Here, we propose a protocol of quadratic quantum Fourier transform (QQFT), considering cold…

Quantum Physics · Physics 2022-11-02 Pei Wang , Zhijuan Huang , Xingze Qiu , Xiaopeng Li

We establish a previously unexplored conservation law for the Quantum Fisher Information Matrix (QFIM) expressed as follows; when the QFIM is constructed from a set of observables closed under commutation, i.e., a Lie algebra, the spectrum…

Quantum Physics · Physics 2025-07-09 Christopher Wilson , John Drew Wilson , Luke Coffman , Shah Saad Alam , Murray J. Holland

In a fiber-based quantum network, utilizing the telecom band is crucial for long-distance quantum information (QI) transmission between quantum nodes. However, the near-infrared wavelength is identified as optimal for processing and storing…

Quantum Physics · Physics 2024-01-19 Po-Han Tseng , Ling-Chun Chen , Jiun-Shiuan Shiu , Yong-Fan Chen

Signal photons emitted by quantum nodes typically fall outside the low-loss telecom window of optical fibers, leading to severe transmission losses. Quantum frequency conversion (QFC) offers an effective optical interface that bridges…

Quantum Physics · Physics 2026-04-28 Zhichuan Liao , Ao Shen , Lai Zhou , Nan Jiang , Zhiliang Yuan

Any technology for quantum information processing (QIP) must embody within it quantum bits (qubits) and maintain control of their key quantum properties of superposition and entanglement. Typical QIP schemes envisage an array of physical…

Quantum Physics · Physics 2009-11-13 Joseph Fitzsimons , Li Xiao , Simon C. Benjamin , Jonathan A. Jones

Properly designed control has been shown to be particularly advantageous for improving AQC accuracy and time complexity scaling. Here, an \emph{in situ} quantum control optimization protocol is developed to indirectly optimize state…

Quantum Physics · Physics 2019-06-12 Gregory Quiroz

With recent improvements in coherence times, superconducting transmon qubits have become a promising platform for quantum computing. They can be flexibly engineered over a wide range of parameters, but also require us to identify an…

Quantum Physics · Physics 2017-09-21 Michael H. Goerz , Felix Motzoi , K. Birgitta Whaley , Christiane P. Koch

Frequency control in power systems is critical to maintaining stability and preventing blackouts. Traditional methods like meta-heuristic algorithms and machine learning face limitations in real-time applicability and scalability. This…

Quantum Physics · Physics 2025-12-03 Younes Ghazagh Jahed , Alireza Khatiri

Quantum machine learning has emerged as a promising tool for pattern recognition, yet many audio-focused approaches still treat spectrograms as generic images and do not explicitly exploit their time-frequency structure. We propose Q-Patch,…

Sound · Computer Science 2026-05-08 Lisan Al Amin , Rakib Hossain , Mahbubul Islam , Faisal Quader , Thanh Thi Nguyen

Controlling and maintaining quantum properties of an open quantum system along its evolution is essential for both fundamental and technological aims. We assess the capability of a frequency-modulated qubit embedded in a leaky cavity to…

We consider a current-biased dc SQUID in the presence of an applied time-dependent bias current or magnetic flux. The phase dynamics of such a Josephson device is equivalent to that of a quantum particle trapped in a $1-$D anharmonic…

Mesoscale and Nanoscale Physics · Physics 2015-05-13 H. Jirari , F. W. J. Hekking , O. Buisson

The accumulation of quantum phase in response to a signal is the central mechanism of quantum sensing, as such, loss of phase information presents a fundamental limitation. For this reason approaches to extend quantum coherence in the…

Quantum property preservation (QPP) is the problem of maintaining a target property of a quantum system for as long as possible. This problem arises naturally in the context of open quantum systems subject to decoherence. Here, we develop a…

Quantum Physics · Physics 2025-02-28 Kumar Saurav , Daniel A. Lidar

Commercially available Noisy Intermediate-Scale Quantum (NISQ) devices now make small hybrid quantum-classical experiments practical, but many tools hide configuration or demand ad-hoc scripting. We introduce the Quantum Experiment…

Quantum Physics · Physics 2025-11-07 Vincent Gierisch , Wolfgang Mauerer

We review a scheme for the systematic design of quantum control protocols based on shortcuts to adiabaticity in few-level quantum systems. The adiabatic dynamics is accelerated by introducing high-frequency modulations in the control…

Quantum Physics · Physics 2024-02-08 Francesco Petiziol , Florian Mintert , Sandro Wimberger

Higher-dimensional quantum systems (qudits) offer advantages in information encoding, error resilience, and compact gate implementations, and naturally arise in platforms such as superconducting and solid-state systems. However, realistic…

Quantum Physics · Physics 2025-06-17 Yule Mayevsky , Akram Youssry , Ritik Sareen , Gerardo A. Paz-Silva , Alberto Peruzzo