J. J. Hope
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View article: Multi-mode cooling of a Bose-Einstein condensate with linear quantum feedback
Multi-mode cooling of a Bose-Einstein condensate with linear quantum feedback Open
We theoretically investigate measurement-based feedback control over the motional degrees of freedom of an oblate quasi-2D atomic Bose-Einstein condensate (BEC) subject to continuous density monitoring. We develop a linear-quadratic-Gaussi…
View article: Multimode feedback cooling of the collective modes of a Bose-Einstein condensate
Multimode feedback cooling of the collective modes of a Bose-Einstein condensate Open
We experimentally demonstrate cavity-free feedback cooling of the three lowest-lying collective modes of a Bose-Einstein condensate in a prolate harmonic trap. Using shadowgraph imaging as an in situ probe of the atomic density, we measure…
View article: High-speed and high-connectivity two-qubit gates in long chains of trapped ions
High-speed and high-connectivity two-qubit gates in long chains of trapped ions Open
We present a theoretical study of fast all-to-all entangling gates in trapped-ion quantum processors, based on impulsive excitation of spin-dependent motion with broadband laser pulses. Previous studies have shown that such fast gate schem…
View article: Stochastic Waveform Estimation at the Fundamental Quantum Limit
Stochastic Waveform Estimation at the Fundamental Quantum Limit Open
Although measuring the deterministic waveform of a weak classical force is a well-studied problem, estimating a random waveform, such as the spectral density of a stochastic signal field, is much less well understood despite it being a wid…
View article: Multi-mode cooling of a Bose-Einstein condensate with linear quantum feedback
Multi-mode cooling of a Bose-Einstein condensate with linear quantum feedback Open
We theoretically investigate measurement-based feedback control over the motional degrees of freedom of an oblate quasi-2D atomic Bose-Einstein condensate (BEC) subject to continuous density monitoring. We develop a linear-quadratic-Gaussi…
View article: Lindblad estimation with fast and precise quantum control
Lindblad estimation with fast and precise quantum control Open
Enhancing precision sensors for stochastic signals using quantum techniques is a promising emerging field of physics. Estimating a weak stochastic waveform is the core task of many fundamental physics experiments including searches for sto…
View article: Fast mixed-species quantum logic gates for trapped-ion quantum networks
Fast mixed-species quantum logic gates for trapped-ion quantum networks Open
Quantum logic operations between physically distinct qubits is an essential aspect of large-scale quantum information processing. We propose an approach to high-speed mixed-species entangling operations in trapped-ion quantum computers, ba…
View article: Effects of Systematic Error on Quantum-Enhanced Atom Interferometry
Effects of Systematic Error on Quantum-Enhanced Atom Interferometry Open
We develop a framework for describing the effects of systematic state preparation error in quantum-enhanced atom interferometry on sensing performance. We do this in the context of both spin-squeezed and non-Gaussian states for the two-axi…
View article: Simulating Feedback Cooling of Incoherent Quantum Mixtures
Simulating Feedback Cooling of Incoherent Quantum Mixtures Open
We develop a new approach for efficient and scalable simulations of measurement and control of quantum systems built upon existing phase-space methods, namely the Truncated Wigner Approximation (TWA). We benchmark against existing particle…
View article: Relative Entropy of Coherence Quantifies Performance in Bayesian Metrology
Relative Entropy of Coherence Quantifies Performance in Bayesian Metrology Open
The ability of quantum states to be in superposition is one of the key features that sets them apart from the classical world. This “coherence” is rigorously quantified by resource theories, which aim to understand how such properties may …
View article: Dual Open Atom Interferometry for Compact and Mobile Quantum Sensing
Dual Open Atom Interferometry for Compact and Mobile Quantum Sensing Open
We demonstrate an atom interferometer measurement protocol compatible with operation on a dynamic platform. Our method employs two open interferometers, derived from the same atomic source, with different interrogation times to eliminate i…
View article: Stochastic waveform estimation at the fundamental quantum limit
Stochastic waveform estimation at the fundamental quantum limit Open
Although measuring the deterministic waveform of a weak classical force is a well-studied problem, estimating a random waveform, such as the spectral density of a stochastic signal field, is much less well-understood despite it being a wid…
View article: The relative entropy of coherence quantifies performance in Bayesian metrology
The relative entropy of coherence quantifies performance in Bayesian metrology Open
The ability of quantum states to be in superposition is one of the key features that sets them apart from the classical world. This `coherence' is rigorously quantified by resource theories, which aim to understand how such properties may …
View article: A hybrid method of generating spin-squeezed states for quantum-enhanced atom interferometry
A hybrid method of generating spin-squeezed states for quantum-enhanced atom interferometry Open
We introduce a new spin-squeezing technique that is a hybrid of two well established spin-squeezing techniques, quantum nondemolition measurement (QND) and one-axis twisting (OAT). This hybrid method aims to improve spin-squeezing over wha…
View article: Achieving the fundamental quantum limit of linear waveform estimation
Achieving the fundamental quantum limit of linear waveform estimation Open
Sensing a classical signal using a linear quantum device is a pervasive application of quantum-enhanced measurement. The fundamental precision limits of linear waveform estimation, however, are not fully understood. In certain cases, there…
View article: Fundamental Limits of Feedback Cooling Ultracold Atomic Gases
Fundamental Limits of Feedback Cooling Ultracold Atomic Gases Open
We investigate the fundamental viability of cooling ultracold atomic gases with quantum feedback control. Our study shows that the trade-off between the resolution and destructiveness of optical imaging techniques imposes constraints on th…
View article: Mutual friction and diffusion of two-dimensional quantum vortices
Mutual friction and diffusion of two-dimensional quantum vortices Open
Dissipation of quantum vortex motion is fundamental to superfluid dynamics and quantum turbulence, yet there is currently a large gap between theory and experiments with ultracold atoms. Here we present a microscopic open quantum systems t…
View article: Signatures of Quantum Gravity in the Gravitational Self-Interaction of Photons
Signatures of Quantum Gravity in the Gravitational Self-Interaction of Photons Open
We propose relativistic tests of quantum gravity using the gravitational self-interaction of photons in a cavity. We demonstrate that this interaction results in a number of quantum gravitational signatures in the quantum state of the ligh…
View article: Feedback cooling Bose gases to quantum degeneracy
Feedback cooling Bose gases to quantum degeneracy Open
Degenerate quantum gases are instrumental in advancing many-body quantum physics and underpin emerging precision sensing technologies. All state-of-the-art experiments use evaporative cooling to achieve the ultracold temperatures needed fo…
View article: Mutual friction and diffusion of two-dimensional quantum vortices
Mutual friction and diffusion of two-dimensional quantum vortices Open
We present a microscopic open quantum systems theory of thermally-damped vortex motion in oblate atomic superfluids that includes previously neglected energy-damping interactions between superfluid and thermal atoms. This mechanism couples…
View article: Twist and Turn Squeezing in a Multi-Mode Bose-Einstein Condensate
Twist and Turn Squeezing in a Multi-Mode Bose-Einstein Condensate Open
Here we examine the generation of Twist and Turn (TNT) Squeezing in a large atom-number Bose-Einstein Condensate for the purposes of generating quantum-enhanced states for atom interferometry. Unlike previous analysis, we examine situation…
View article: Superflow decay in a toroidal Bose gas: The effect of quantum and thermal fluctuations
Superflow decay in a toroidal Bose gas: The effect of quantum and thermal fluctuations Open
We theoretically investigate the stochastic decay of persistent currents in a toroidal ultracold atomic superfluid caused by a perturbing barrier. Specifically, we perform detailed three-dimensional simulations to model the experiment of K…
View article: Report on 2105.03154v2
Report on 2105.03154v2 Open
We theoretically investigate the stochastic decay of persistent currents in a toroidal ultracold atomic superfluid caused by a perturbing barrier.Specifically, we perform detailed threedimensional simulations to model the experiment of Kum…
View article: Report on scipost_202105_00011v1
Report on scipost_202105_00011v1 Open
We theoretically investigate the stochastic decay of persistent currents in a toroidal ultracold atomic superfluid caused by a perturbing barrier.Specifically, we perform detailed three-dimensional simulations to model the experiment of Ku…
View article: Fast entangling gates in long ion chains
Fast entangling gates in long ion chains Open
We present a model for implementing fast entangling gates (∼1 μs) with ultrafast pulses in arbitrarily long ion chains, that requires low numbers of pulses and can be implemented with laser repetition rates well within experimental capabil…
View article: Scalable quantum computation with fast gates in two-dimensional microtrap arrays of trapped ions
Scalable quantum computation with fast gates in two-dimensional microtrap arrays of trapped ions Open
We theoretically investigate the use of fast pulsed two-qubit gates for trapped ion quantum computing in a two-dimensional microtrap architecture. In one dimension, such fast gates are optimal when employed between nearest neighbors, and w…
View article: Dynamics and stability of an optically levitated mirror
Dynamics and stability of an optically levitated mirror Open
We analyse the dynamics of a one-dimensional vertical Fabry-Perot cavity, where the upper mirror levitates due to intra-cavity radiation pressure force. A perturbative approach is used based around separation of timescales, which allows us…
View article: Optimized fast gates for quantum computing with trapped ions
Optimized fast gates for quantum computing with trapped ions Open
We present an efficient approach to optimizing pulse sequences for implementing fast entangling two-qubit gates on trapped ion quantum information processors. We employ a two-phase procedure for optimizing gate fidelity, which we demonstra…
View article: Micromotion-enhanced fast entangling gates for trapped-ion quantum computing
Micromotion-enhanced fast entangling gates for trapped-ion quantum computing Open
Radio-frequency-induced micromotion in trapped ion systems is typically minimized or circumvented to avoid off-resonant couplings for adiabatic processes such as multi-ion gate operations. Nonadiabatic entangling gates (so-called "fast gat…