arXiv subjects

Nathan Shettell

Publications and source records attributed to Nathan Shettell.

13 recordsLinked to original sources

arXiv2026

Field-Deployable Hybrid Gravimetry: Projecting Absolute Accuracy Across a Remote 24km$^2$ Survey via Daily Quantum Calibration

Absolute gravimeters deliver drift-free, high-precision measurements but are typically bulky and difficult to deploy, whereas relative gravimeters are lightweight and mobile but intrinsically limited by time-dependent drift. We demonstrate a hybrid quantum-enabled gravimetry approach in which an on-site atomic gravimeter provides routine, $μ$Gal-level calibration of two mobile spring gravimeters during a field survey spanning 24 km$^2$ of dense tropical terrain. The atomic reference enables high-precision, asynchronous cross-comparison of relative measurements acquired over seven days, effectively suppressing instrumental drift to a level required for demanding geophysical applications. This deployment captures regional gravity gradients with high fidelity under challenging environmental conditions, illustrating how field-operable quantum sensors can extend quantum-grade gravimetry beyond laboratory settings and serve as scalable calibration backbones for large-area, high-precision geophysical surveys in remote or logistically constrained environments.

physics.geo-ph↗

arXiv2026

Entropic Efficiency of Bayesian Inference Protocols

Inference is a versatile tool that underlies scientific discovery, machine learning, and everyday decision-making: it describes how an agent updates a probability distribution as partial information is acquired from multiple measurements, reducing ignorance about a system's latent state. We define an inferential efficiency as the ratio of information gain to cumulative memory erasure cost, with inefficiency arising from unexploited correlations between the measured system and memories, and/or between memories and environment (noise). Using this efficiency, we benchmark two limiting measurement paradigms: sequential, in which the same memory is exploited iteratively, and parallel, in which many memories are exploited simultaneously. In both cases, the minimal erasure cost reflects correlations across memories: temporal in sequential, spatial in parallel. Remarkably, when all system-memory correlations are exploited for inference, both paradigms attain the same minimal erasure cost, even in the presence of noise. Conversely, the parallel paradigm performs better in the presence of unexploited correlations, stemming from hidden memories' degrees of freedom. This approach provides a quantitative, physically grounded criterion to compare inference strategies, determine their efficiency, and link target information gains to their minimal entropic cost.

cond-mat.stat-mech↗

arXiv2025

Exclusive Control of Quantum Memory Erasure

Erasing memory is a fundamental operational task in quantum information processing, governed by Landauer's principle, which links information loss to thermodynamic work. We introduce and analyze assisted quantum erasure, where correlations with a remote system reduce the energetic cost of resetting a memory. We identify exclusive control of erasure as the central operational requirement: only a designated party should be able to achieve the minimal cost, while any adversary necessarily fails. In the device-dependent regime, we show that entanglement of formation exactly characterizes exclusivity, establishing entanglement as the decisive thermodynamic resource. Moving to a one-sided device-independent scenario, in which only the memory holder's device is trusted, we develop an operational erasure protocol based on random dephasing and conditional operations. These results elevate quantum erasure from a thermodynamic constraint to an operational primitive: the erasure work cost quantifies secure, exclusive control over quantum memory, guaranteeing that an unauthorized agent cannot fully erase information under bounded work.

quant-ph↗

arXiv2024

Geophysical survey based on Hybrid Gravimetry using Relative Measurements and an Atomic Gravimeter as an Absolute Reference

Gravimetry is a versatile metrological approach in geophysics to accurately map subterranean mass and density anomalies. There is a broad diversification regarding the working principle of gravimeters, wherein atomic gravimeters are one of the most technologically progressive class of gravimeters which can monitor gravity at an absolute scale with a high-repetition without exhibiting drift. Despite the apparent utility for geophysical surveys, atomic gravimeters are (currently) laboratory-bound devices due to the vexatious task of transportation. Here, we demonstrated the utility of an atomic gravimeter on-site during a gravity survey, where the issue of immobility was circumvented with a relative spring gravimeter. The atomic gravimeter served as a means to map the relative data from the spring gravimeter to an absolute measurement with an effective precision of 7.7$μ$Gal. Absolute measurements provide a robust and feasible method to define and control gravity data taken at different sites, or a later date, which is critical to analyze underground geological units, in particular when it is combined with other geophysical approaches.

physics.atom-ph↗

arXiv2023

Emulating an Atomic Gyroscope with Multiple Accelerometers

The main advantage of an atomic accelerometer when compared to a classical accelerometer is negligible bias drift, allowing for stable long-term measurements, which opens the potential application in navigation. This negligible drift arises from the fact that the measurements can be traced back to natural constants, and the system is intrinsically stable due to the simple design. In this manuscript, we extend this property of long-term stability to gyroscopic measurements by considering an array of atomic accelerometers, and comparing the performance to atomic gyroscopes, which are technologically more prone to bias drifts. We demonstrate that an array consisting of four three-axis atomic accelerometers can outperform state of the art atomic gyroscopes with respect to long-term stability.

physics.atom-ph↗

arXiv2023

Bounding the Minimum Time of a Quantum Measurement

Measurements take a singular role in quantum theory. While they are often idealized as an instantaneous process, this is in conflict with all other physical processes in nature. In this Letter, we adopt a standpoint where the interaction with an environment is a crucial ingredient for the occurrence of a measurement. Within this framework, we derive lower bounds on the time needed for a measurement to occur. Our bound scales proportionally to the change in entropy of the measured system, and decreases as the number of of possible measurement outcomes or the interaction strength driving the measurement increases. We evaluate our bound in two examples where the environment is modelled by bosonic modes and the measurement apparatus is modelled by spins or bosons.

quant-ph↗

arXiv2022

Quantum Metrology with Delegated Tasks

A quantum metrology scheme can be decomposed into three quantum tasks: state preparation, parameter encoding and measurements. Consequently, it is imperative to have access to the technologies which can execute the aforementioned tasks to fully implement a quantum metrology scheme. In the absence of one or more of these technologies, one can proceed by delegating the tasks to a third party. However, doing so has security ramifications: the third party can bias the result or leak information. In this article, we outline different scenarios where one or more tasks are delegated to an untrusted (and possibly malicious) third party. In each scenario, we outline cryptographic protocols which can be used to circumvent malicious activity. Further, we link the effectiveness of the quantum metrology scheme to the soundness of the cryptographic protocols.

quant-ph↗

arXiv2022

Private network parameter estimation with quantum sensors

Networks of quantum sensors are a central application of burgeoning quantum networks. A key question for the use of such networks will be their security, particularly against malicious participants of the network. We introduce a protocol to securely evaluate linear functions of parameters over a network of quantum sensors, ensuring that all parties only have access to the function value, and no access to the individual parameters. This has application to secure networks of clocks and opens the door to more general applications of secure multiparty computing to networks of quantum sensors.

quant-ph↗

arXiv2022

Quantum Information Techniques for Quantum Metrology

Quantum metrology is an auspicious discipline of quantum information which is currently witnessing a surge of experimental breakthroughs and theoretical developments. The main goal of quantum metrology is to estimate unknown parameters as accurately as possible. By using quantum resources as probes, it is possible to attain a measurement precision that would be otherwise impossible using the best classical strategies. For example, with respect to the task of phase estimation, the maximum precision (the Heisenberg limit) is a quadratic gain in precision with respect to the best classical strategies. Of course, quantum metrology is not the sole quantum technology currently undergoing advances. The theme of this thesis is exploring how quantum metrology can be enhanced with other quantum techniques when appropriate, namely: graph states, error correction and cryptography.

quant-ph↗

arXiv2022

Cryptographic approach to Quantum Metrology

We consider a cryptographically motivated framework for quantum metrology in the presence of a malicious adversary. We begin by devising an estimation strategy for a (potentially) altered resource (due to a malicious adversary) and quantify the amount of bias and the loss in precision as a function of the introduced uncertainty in the resource. By incorporating an appropriate cryptographic protocol, the uncertainty in the resource can be bounded with respect to the soundness of the cryptographic protocol. Thus the effectiveness of the quantum metrology problem can be directly related to the effectiveness of the cryptography protocol. As an example, we consider a quantum metrology problem in which resources are exchanged through an unsecured quantum channel. We then construct two protocols for this task which offer a trade-off between difficulty of implementation and efficiency.

quant-ph↗

arXiv2021

Robust quantum metrology with explicit symmetric states

Quantum metrology is a promising practical use case for quantum technologies, where physical quantities can be measured with unprecedented precision. In lieu of quantum error correction procedures, near term quantum devices are expected to be noisy, and we have to make do with noisy probe states. We prove that, for a set of carefully chosen symmetric probe states that lie within certain quantum error correction codes, quantum metrology exhibits an advantage over classical metrology even after the probe states are corrupted by a constant number of erasure and dephasing errors. These probe states prove useful for robust metrology not only in the NISQ regime, but also in the asymptotic setting where they achieve Heisenberg scaling. This brings us closer towards making robust quantum metrology a technological reality.

quant-ph↗

arXiv2021

Practical Limits of Error Correction for Quantum Metrology

Noise is the greatest obstacle in quantum metrology that limits it achievable precision and sensitivity. There are many techniques to mitigate the effect of noise, but this can never be done completely. One commonly proposed technique is to repeatedly apply quantum error correction. Unfortunately, the required repetition frequency needed to recover the Heisenberg limit is unachievable with the existing quantum technologies. In this article we explore the discrete application of quantum error correction with current technological limitations in mind. We establish that quantum error correction can be beneficial and highlight the factors which need to be improved so one can reliably reach the Heisenberg limit level precision.

quant-ph↗

arXiv2020

Graph States as a Resource for Quantum Metrology

By using highly entangled states, quantum metrology guarantees precision impossible with classical measurements. Unfortunately such states can be very susceptible to noise, and it is a great challenge of the field to maintain quantum advantage in realistic conditions. In this study we investigate the practicality of graph states for quantum metrology. Graph states are a natural resource for much of quantum information, and here we characterize their quantum Fisher information (QFI) for an arbitrary graph state. We then construct families of graph states which approximately achieves the Heisenberg limit, we call these states bundled graph states. We demonstrate that bundled graph states maintain a quantum advantage after being subjected to iid dephasing or finite erasures. This shows that these graph states are good resources for robust quantum metrology. We also quantify the number of n qubit stabilizer states that are useful as a resource for quantum metrology.

quant-ph↗