A5066547430- Quantum Computing Algorithms and Architecture
- Quantum Information and Cryptography
- Quantum many-body systems
- Quantum and electron transport phenomena
- Semiconductor materials and devices
- Neural Networks and Applications
- Laser-Matter Interactions and Applications
- Quantum Mechanics and Applications
- Photonic and Optical Devices
- Advanced Chemical Physics Studies
- Magnetism in coordination complexes
- Matrix Theory and Algorithms
- Electron Spin Resonance Studies
- Numerical Methods and Algorithms
- Quantum chaos and dynamical systems
- Blind Source Separation Techniques
- Physics of Superconductivity and Magnetism
- Semiconductor Quantum Structures and Devices
- Spectroscopy and Quantum Chemical Studies
- Neural Networks and Reservoir Computing
- Black Holes and Theoretical Physics
- Computability, Logic, AI Algorithms
- Quantum optics and atomic interactions
- Machine Learning in Materials Science
- Advanced NMR Techniques and Applications
Leiden University
2020-2025
Google (United States)
2022
University of California, Riverside
2022
Huygens Institute for History and Culture of the Netherlands
2021
The accumulation of noise in quantum computers is the dominant issue stymieing push algorithms beyond their classical counterparts. We do not expect to be able afford overhead required for error correction next decade, so meantime we must rely on low-cost, unscalable mitigation techniques bring computing its full potential. In this paper present a new technique based phase estimation that can also reduce errors expectation value (e.g., variational algorithms). general idea apply while...
Conical intersections are topologically protected crossings between the potential energy surfaces of a molecular Hamiltonian, known to play an important role in chemical processes such as photoisomerization and non-radiative relaxation. They characterized by non-zero Berry phase, which is topological invariant defined on closed path atomic coordinate space, taking value <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>&#x03C0;</mml:mi></mml:math> when encircles...
We consider a quantum computation that only extracts one bit of information per $N$-qubit state preparation. This is relevant for error mitigation schemes where the remainder system measured to detect errors. optimize estimation expectation value an operator by its linear decomposition into bitwise-measurable terms. prove optimal decompositions must be in terms reflections with eigenvalues $\ifmmode\pm\else\textpm\fi{}1$. find reflection fast-forwardable operator, and show numerical...
Embedding techniques allow the efficient description of correlations within localized fragments large molecular systems while accounting for their environment at a lower level theory. We introduce FragPT2: novel embedding framework that addresses multiple interacting active fragments. Fragments are assigned separate spaces, constructed by localizing canonical orbitals. Each fragment is then solved with multireference method, self-consistently embedded in mean field from other Finally,...
Abstract The search for useful applications of noisy intermediate-scale quantum (NISQ) devices in simulation has been hindered by their intrinsic noise and the high costs associated with achieving accuracy. A promising approach to finding utility despite these challenges involves using generate training data classical machine learning (ML) models.&#xD;In this study, we explore use generated algorithms an ML model learn a density functional Fermi-Hubbard model. We benchmark various models...
We introduce a method for digital preparation of ground states simulated Hamiltonians, inspired by cooling in nature and adapted to leverage the capabilities quantum hardware. The cold bath is single ancillary qubit, which reset periodically coupled system non-perturbatively. Studying this on 1-qubit toy model, we optimize two protocols based weak-coupling strong-coupling approaches. Extending insight from develop scalable larger systems. LogSweep protocol extends approach sweeping energies...
An important measure of the development quantum computing platforms has been simulation increasingly complex physical systems. Prior to fault-tolerant computing, robust error mitigation strategies are necessary continue this growth. Here, we study within seniority-zero electron pairing subspace, which affords both a computational stepping stone fully correlated model, and an opportunity validate recently introduced ``purification-based'' error-mitigation strategies. We compare performance...
Coherent optical states consist of a quantum superposition different photon number (Fock) states, but because they do not form an orthogonal basis, no can be obtained from it by linear optics. Here we demonstrate the reverse, manipulating random continuous single-photon stream using interference in Sagnac loop, create engineered light with tunable statistics, including approximate weak coherent states. We this experimentally true produced semiconductor dot microcavity, and show that obtain...
Transitions out of the ground space limit performance quantum adiabatic algorithms, while hardware imperfections impose stringent limitations on circuit depth. We propose an echo verification protocol which mitigates both coherent and incoherent errors, arising from non-adiabatic transitions noise, respectively. Quasi-adiabatically evolving forward backward allows for echo-verified measurement any observable. In addition to mitigating our method uses positive-time dynamics only. Crucially,...
Parameter shift rules enable the estimation of derivatives expectation values with respect to dynamical evolution a state. Thus, they provide valuable tool in variational optimization and insight into behavior quantum systems. Constructing parameter applicable complex generators is useful towards improving control analog simulation devices extending applicability simulating methods. However, are typically designed only for highly degenerate or equidistant eigenvalues, such as Pauli...
Embedding techniques allow the efficient description of correlations within localized fragments large molecular systems, while accounting for their environment at a lower level theory. We introduce FragPT2: novel embedding framework that addresses multiple interacting active fragments. Fragments are assigned separate spaces, constructed by localizing canonical orbitals. Each fragment is then solved with multi-reference method, self-consistently embedded in mean field from other Finally,...
The search for useful applications of noisy intermediate-scale quantum (NISQ) devices in simulation has been hindered by their intrinsic noise and the high costs associated with achieving accuracy. A promising approach to finding utility despite these challenges involves using generate training data classical machine learning (ML) models. In this study, we explore use generated algorithms an ML model learn a density functional Fermi-Hubbard model. We benchmark various models against exact...
As fully fault-tolerant quantum computers capable of solving useful problems remain a future goal, we anticipate an era "early fault tolerance" allowing for limited error correction. We propose framework designing early algorithms by trading between correction overhead and residual logical noise, apply it to phase estimation (QPE). develop quantum-Fourier-transform (QFT)-based QPE technique that is robust global depolarising noise outperforms the previous state art at low moderate rates....
To apply the powerful many-body techniques of tensor networks to massless Dirac fermions, one wants discretize <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mrow><a:mi mathvariant="bold-italic">p</a:mi><a:mo>·</a:mo><a:mrow><a:mi mathvariant="bold-italic">σ</a:mi></a:mrow></a:mrow></a:math> Hamiltonian and construct a matrix-product-operator (MPO) representation. We compare two alternative discretization schemes, with sine dispersion, other tangent applied one-dimensional Luttinger...
Abstract An important measure of the development quantum computing platforms has been simulation increasingly complex physical systems [1–3]. Prior to fault-tolerant computing, robust error mitigation strategies are necessary continue this growth [4–11]. Here, we study within seniority-zero electron pairing subspace, which affords both a computational stepping stone fully correlated model [12–17], and an opportunity validate recently introduced “purification-based” error-mitigation [8–10]....
Conical intersections are topologically protected crossings between the potential energy surfaces of a molecular Hamiltonian, known to play an important role in chemical processes such as photoisomerization and non-radiative relaxation. They characterized by non-zero Berry phase, which is topological invariant defined on closed path atomic coordinate space, taking value $\pi$ when encircles intersection manifold. In this work, we show that for real Hamiltonians, phase can be obtained tracing...
Transitions out of the ground space limit performance quantum adiabatic algorithms, while hardware imperfections impose stringent limitations on circuit depth. We propose an echo verification protocol which mitigates both coherent and incoherent errors, arising from non-adiabatic transitions noise, respectively. Quasi-adiabatically evolving forward backwards allows for echo-verified measurement any observable. In addition to mitigating our method uses positive-time dynamics only. Crucially,...
We consider a quantum computation that only extracts one bit of information per $N$-qubit state preparation. This is relevant for error mitigation schemes where the remainder system measured to detect errors. optimize estimation expectation value an operator by its linear decomposition into bitwise-measurable terms. prove optimal decompositions must be in terms reflections with eigenvalues $\pm1$. find reflection fast-forwardable operator, and show numerical improvement over simple Pauli...