David R. M. Arvidsson-Shukur
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View article: Risk-minimizing states for the quantum-phase-estimation algorithm
Risk-minimizing states for the quantum-phase-estimation algorithm Open
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…
View article: Risk-minimizing states for the quantum-phase-estimation algorithm
Risk-minimizing states for the quantum-phase-estimation algorithm Open
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…
View article: Minimal state-preparation times for silicon spin qubits
Minimal state-preparation times for silicon spin qubits Open
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 …
View article: Superconducting antiqubits achieve optimal phase estimation via unitary inversion
Superconducting antiqubits achieve optimal phase estimation via unitary inversion Open
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 p…
View article: Risk-minimizing states for the quantum-phase-estimation algorithm
Risk-minimizing states for the quantum-phase-estimation algorithm Open
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…
View article: Properties and applications of the Kirkwood–Dirac distribution
Properties and applications of the Kirkwood–Dirac distribution Open
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 qua…
View article: Contextuality Can be Verified with Noncontextual Experiments
Contextuality Can be Verified with Noncontextual Experiments Open
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 ``K…
View article: Compression of metrological quantum information in the presence of noise
Compression of metrological quantum information in the presence of noise Open
In quantum metrology, information about unknown parameters θ=(θ1,...,θM) is accessed by measuring probe states ρ̂θ. In experimental settings where copies of ρ̂θ can be produced rapidly (e.g., in optics), the information-extraction bottleneck…
View article: Agnostic Phase Estimation
Agnostic Phase Estimation Open
The goal of quantum metrology is to improve measurements' sensitivities by harnessing quantum resources. Metrologists often aim to maximize the quantum Fisher information, which bounds the measurement setup's sensitivity. In studies of fun…
View article: Minimal evolution times for fast, pulse-based state preparation in silicon spin qubits
Minimal evolution times for fast, pulse-based state preparation in silicon spin qubits Open
Standing as one of the most significant barriers to reaching quantum advantage, state-preparation fidelities on noisy intermediate-scale quantum processors suffer from quantum-gate errors, which accumulate over time. A potential remedy is …
View article: The set of Kirkwood-Dirac positive states is almost always minimal
The set of Kirkwood-Dirac positive states is almost always minimal Open
A central problem in quantum information is determining quantum-classical boundaries. A useful notion of classicality is provided by the quasiprobability formulation of quantum theory. In this framework, a state is called classical if it i…
View article: Layering and subpool exploration for adaptive variational quantum eigensolvers: Reducing circuit depth, runtime, and susceptibility to noise
Layering and subpool exploration for adaptive variational quantum eigensolvers: Reducing circuit depth, runtime, and susceptibility to noise Open
Adaptive variational quantum eigensolvers (ADAPT-VQEs) are promising candidates for simulations of strongly correlated systems on near-term quantum hardware. To further improve the noise resilience of these algorithms, recent efforts have …
View article: Adaptive Bayesian quantum algorithm for phase estimation
Adaptive Bayesian quantum algorithm for phase estimation Open
Quantum-phase-estimation algorithms are critical subroutines in many applications for quantum computers and in quantum-metrology protocols. These algorithms estimate the unknown strength of a unitary evolution. By using coherence or entang…
View article: James-Stein Estimation in Quantum Gaussian Sensing
James-Stein Estimation in Quantum Gaussian Sensing Open
The James-Stein estimator is a biased estimator -- for a finite number of samples its expected value is not the true mean. The maximum-likelihood estimator (MLE), is unbiased and asymptotically optimal. Yet, when estimating the mean of $3$…
View article: Dynamic adaptive quantum approximate optimization algorithm for shallow, noise-resilient circuits
Dynamic adaptive quantum approximate optimization algorithm for shallow, noise-resilient circuits Open
The quantum approximate optimization algorithm (QAOA) is an appealing proposal to solve NP problems on noisy intermediate-scale quantum (NISQ) hardware. Making NISQ implementations of the QAOA resilient to noise requires short ansatz circu…
View article: Landscape-Scale Mining and Water Management in a Hyper-Arid Catchment: The Cuajone Mine, Moquegua, Southern Peru
Landscape-Scale Mining and Water Management in a Hyper-Arid Catchment: The Cuajone Mine, Moquegua, Southern Peru Open
The expansion of copper mining on the hyper-arid pacific slope of Southern Peru has precipitated growing concern for scarce water resources in the region. Located in the headwaters of the Torata river, in the department of Moquegua, the Cu…
View article: Landscape-Scale Mining and Water Management in a Hyper-Arid Catchment: The Cuajone Mine, Moquegua, Southern Peru
Landscape-Scale Mining and Water Management in a Hyper-Arid Catchment: The Cuajone Mine, Moquegua, Southern Peru Open
The expansion of copper mining on the hyper-arid pacific slope of southern Peru has precipitated growing concern for scarce water resources in the region. Located in the headwaters of the Torata river, in the department of Moquegua, the Cu…
View article: Quantifying the effect of gate errors on variational quantum eigensolvers for quantum chemistry
Quantifying the effect of gate errors on variational quantum eigensolvers for quantum chemistry Open
Variational quantum eigensolvers (VQEs) are leading candidates to demonstrate near-term quantum advantage. Here, we conduct density-matrix simulations of leading gate-based VQEs for a range of molecules. We numerically quantify their level…
View article: Nonclassical Advantage in Metrology Established via Quantum Simulations of Hypothetical Closed Timelike Curves
Nonclassical Advantage in Metrology Established via Quantum Simulations of Hypothetical Closed Timelike Curves Open
We construct a metrology experiment in which the metrologist can sometimes amend the input state by simulating a closed timelike curve, a worldline that travels backward in time. The existence of closed timelike curves is hypothetical. Nev…
View article: Dynamic-ADAPT-QAOA: An algorithm with shallow and noise-resilient circuits
Dynamic-ADAPT-QAOA: An algorithm with shallow and noise-resilient circuits Open
The quantum approximate optimization algorithm (QAOA) is an appealing proposal to solve NP problems on noisy intermediate-scale quantum (NISQ) hardware. Making NISQ implementations of the QAOA resilient to noise requires short ansatz circu…
View article: Layering and subpool exploration for adaptive Variational Quantum Eigensolvers: Reducing circuit depth, runtime, and susceptibility to noise
Layering and subpool exploration for adaptive Variational Quantum Eigensolvers: Reducing circuit depth, runtime, and susceptibility to noise Open
Adaptive variational quantum eigensolvers (ADAPT-VQEs) are promising candidates for simulations of strongly correlated systems on near-term quantum hardware. To further improve the noise resilience of these algorithms, recent efforts have …
View article: Compression of metrological quantum information in the presence of noise
Compression of metrological quantum information in the presence of noise Open
In quantum metrology, information about unknown parameters $\mathbfθ = (θ_1,\ldots,θ_M)$ is accessed by measuring probe states $\hatρ_{\mathbfθ}$. In experimental settings where copies of $\hatρ_{\mathbfθ}$ can be produced rapidly (e.g., i…
View article: Characterizing the geometry of the Kirkwood-Dirac positive states
Characterizing the geometry of the Kirkwood-Dirac positive states Open
The Kirkwood-Dirac (KD) quasiprobability distribution can describe any quantum state with respect to the eigenbases of two observables $A$ and $B$. KD distributions behave similarly to classical joint probability distributions but can assu…
View article: Only Classical Parameterised States have Optimal Measurements under Least Squares Loss
Only Classical Parameterised States have Optimal Measurements under Least Squares Loss Open
Measurements of quantum states form a key component in quantum-information processing. It is therefore an important task to compare measurements and furthermore decide if a measurement strategy is optimal. Entropic quantities, such as the …
View article: An adaptive Bayesian quantum algorithm for phase estimation
An adaptive Bayesian quantum algorithm for phase estimation Open
Quantum-phase-estimation algorithms are critical subroutines in many applications for quantum computers and in quantum-metrology protocols. These algorithms estimate the unknown strength of a unitary evolution. By using coherence or entang…
View article: Coherence protection of spin qubits in hexagonal boron nitride
Coherence protection of spin qubits in hexagonal boron nitride Open
Spin defects in foils of hexagonal boron nitride are an attractive platform for magnetic field imaging, since the probe can be placed in close proximity to the target. However, as a III-V material the electron spin coherence is limited by …
View article: Quantifying the effect of gate errors on variational quantum eigensolvers for quantum chemistry
Quantifying the effect of gate errors on variational quantum eigensolvers for quantum chemistry Open
Variational quantum eigensolvers (VQEs) are leading candidates to demonstrate near-term quantum advantage. Here, we conduct density-matrix simulations of leading gate-based VQEs for a range of molecules. We numerically quantify their level…
View article: Nonclassical advantage in metrology established via quantum simulations of hypothetical closed timelike curves
Nonclassical advantage in metrology established via quantum simulations of hypothetical closed timelike curves Open
We construct a metrology experiment in which the metrologist can sometimes amend her input state by simulating a closed timelike curve, a worldline that travels backward in time. The existence of closed timelike curves is hypothetical. Nev…
View article: An iterative quantum-phase-estimation protocol for near-term quantum hardware
An iterative quantum-phase-estimation protocol for near-term quantum hardware Open
Given $N_{\textrm{tot}}$ applications of a unitary operation with an unknown phase $θ$, a large-scale fault-tolerant quantum system can {reduce} an estimate's {error} scaling from $\mathcal{O} \left[ 1 / \sqrt{N_{\textrm{tot}}} \right]$ to…
View article: Negative Quasiprobabilities Enhance Phase Estimation in Quantum-Optics Experiment
Negative Quasiprobabilities Enhance Phase Estimation in Quantum-Optics Experiment Open
Operator noncommutation, a hallmark of quantum theory, limits measurement precision, according to uncertainty principles. Wielded correctly, though, noncommutation can boost precision. A recent foundational result relates a metrological ad…