David R. M. Arvidsson-Shukur

QuGradLab

Christopher K. Long, Henrik Gothen, C. H. W. Barnes, David R. M. Arvidsson-Shukur et autres

An extension to the Python package QuGrad that implements common Hilbert space structures, Hamiltonians, and pulse shapes for quantum control.

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Almost sure minimality of the set of experiments with classical Kirkwood-Dirac representations

Christopher Langrenez, Wilfred Salmon, Stephan De Bièvre, Jonathan J. Thio et autres

A central problem in quantum information is determining quantum-classical boundaries. In the quasiprobability framework, a state is called classical if it is represented by a quasiprobability distribution that is positive, and thus a probability distribution. In recent years, the Kirkwood-Dirac (KD) distributions …

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Risk-minimizing states for the quantum-phase-estimation algorithm

Joseph G. Smith, C. H. W. Barnes, David R. M. Arvidsson-Shukur

The quantum-phase-estimation algorithm (QPEA) is widely used to find estimates of unknown phases. The original algorithm relied on an input state in a uniform superposition of all possible bit strings. However, it is known that other input states can reduce certain Bayesian …

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Minimal state-preparation times for silicon spin qubits

Christopher K. Long, Nicholas J. Mayhall, Sophia E. Economou, Edwin Barnes et autres

Abstract Efficient preparation of quantum states on noisy intermediate-scale quantum processors remains a significant challenge to achieve quantum advantage. While gate-based methods have been the traditional approach, pulse-based algorithms offer promising alternatives with finer control and potentially reduced overheads. Here, we leverage …

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Kirkwood-Dirac Nonpositivity is a Necessary Resource for Quantum Computing

Jonathan J. Thio, Songqinghao Yang, Nicole Yunger Halpern, Stephan De Bièvre et autres

We elucidate the boundary between classical and quantum computation by constructing qubit Clifford circuits with nonstabilizer inputs that can be efficiently simulated classically. We do so by casting the quantum circuits realizable by defect braiding in the surface code in terms of …

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Superconducting antiqubits achieve optimal phase estimation via unitary inversion

Xingrui Song, Surihan Sean Borjigin, F Salvati, Yuxin Wang et autres

A positron is equivalent to an electron traveling backward through time. Casting transmon superconducting qubits as akin to electrons, we simulate a positron with a transmon subject to particular resonant and off-resonant drives. We call positron-like transmons "antiqubits." An antiqubit's effective gyromagnetic …

Convex roofs witnessing Kirkwood–Dirac nonpositivity

Christopher Langrenez, David R. M. Arvidsson-Shukur, Stephan De Bièvre

Abstract Given two orthonormal bases ( | a i ⟩ ) i and ( | b j ⟩ ) j , one can associate to every quantum state a Kirkwood–Dirac (KD) quasiprobability distribution. KD distributions are like joint classical probabilities except that …

fr, gb (code pays fourni par la source)

Risk-minimizing states for the quantum-phase-estimation algorithm

Joseph G. Smith, C. H. W. Barnes, David R. M. Arvidsson-Shukur

The quantum-phase-estimation algorithm (QPEA) is widely used to find estimates of unknown phases. The original algorithm relied on an input state in a uniform superposition of all possible bit strings. However, it is known that other input states can reduce certain Bayesian …

Agnostic phase estimation for quantum sensing and quantum computation

F Salvati, Xingrui Song, Chandrashekhar Gaikwad, Nicole Yunger Halpern et autres

Phase estimation is crucial to quantum-information processing. Several quantum algorithms use phase estimation as a subroutine for finding unitary operators’ eigenvalues. Furthermore, phase estimation is used in quantum metrology, the field of using quantum systems to probe, measure, and estimate unknown physical …

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Properties and applications of the Kirkwood–Dirac distribution

David R. M. Arvidsson-Shukur, William F. Braasch, Stephan De Bièvre, Justin Dressel et autres

Abstract There are several mathematical formulations of quantum mechanics. The Schrödinger picture expresses quantum states in terms of wavefunctions over, e.g. position or momentum. Alternatively, phase-space formulations represent states with quasi-probability distributions over, e.g. position and momentum. A quasi-probability distribution resembles a …

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Contextuality Can be Verified with Noncontextual Experiments

Jonathan J. Thio, Wilfred Salmon, C. H. W. Barnes, Stephan De Bièvre et autres

We uncover new features of generalized contextuality by connecting it to the Kirkwood-Dirac (KD) quasiprobability distribution. Quantum states can be represented by KD distributions, which take values in the complex unit disc. Only for ``KD-positive'' states are the KD distributions joint probability …

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Compression of metrological quantum information in the presence of noise

Flavio Salvati, Wilfred Salmon, C. H. W. Barnes, David R. M. Arvidsson-Shukur

In quantum metrology, information about unknown parameters θ = ( θ 1 , ... , θ M ) is accessed by measuring probe states ρ ̂ θ . In experimental settings where copies of ρ ̂ θ can be produced rapidly (e.g., …

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