Tommy Chin, Theoretical Physicist at Penn State (Open Quantum Systems)

Tommy Chin

PhD Candidate in Physics

Institute for Gravitation & the Cosmos, The Pennsylvania State University

I build theoretical frameworks that infer global properties of an open quantum system from ensembles of local subsystem descriptions.

Research

I work with Prof. Sarah Shandera in the Institute for Gravitation and the Cosmos on the theory of open quantum systems. I study how excitation, correlation, and information move through quantum networks whose subsystems couple to environments no measurement can reach.

I expect to defend in May 2028 and am applying for postdoctoral positions in open quantum systems and related areas of theoretical physics, beginning Fall 2028.

Publications

A fully connected N-qubit network partitioned into four open subsystems, each described by a reduced density matrix.

2026 · Preprint

Excitation Flow, Positivity, and Fisher Information for Open Subsystems of an N-Qubit Network

T. Chin, S. Shandera

arXiv:2605.15036 [quant-ph] (2026) · Under review at Physical Review A

I study the reduced dynamics of K-qubit subsystems of larger qubit networks, where the direction of excitation flow determines whether the propagator remains positive and completely positive. Quantum Fisher information sets what local measurements recover about the global network.

arXiv

Eigenvalue distribution in the unit disk for a non-phase-covariant qubit ensemble.

2024 · Peer-reviewed

Effective Dynamics of Qubit Networks via Phase-Covariant Quantum Ensembles

S. Prudhoe, U. Akhouri, T. Chin, S. Shandera

Open Systems & Information Dynamics 31, 2450016 (2024)

Effective subsystem dynamics often require an ensemble of propagators rather than a single generator. I work on which ensembles admit closed-form treatment and where departures from phase covariance mark the limits of that description.

DOI arXiv

A 3 by 3 array of cubes showing strain and dark-state orientation configurations for silicon-vacancy centers.

In preparation

Impact of Strain and Dark States on Spectroscopic Measurements of Silicon-Vacancy Centers in Diamond

T. Chin, K. Narayan, I. Bashir, K. M. Bates, L. G. Stanton, E. Khatami, C. L. Smallwood

Manuscript in preparation

I built the Monte Carlo and GPU simulations relating strain distributions and dark-state structure in silicon-vacancy centers to measured photoluminescence spectra, in collaboration with an experimental group.

Selected Talks

Apr 2026Invited talk, “Non-Markovian Dynamics and Fisher Information of Qubits,” Open Quantum Systems: Dissipation and Decoherence from Subatomic to Cosmic Scales, Mainz Institute for Theoretical Physics (MITP), Johannes Gutenberg University Mainz.

Nov 2025“Ensembles of Propagators, Not Single Hamiltonians, Govern Open Quantum Dynamics,” APS Mid-Atlantic Section Meeting 2025, Penn State Harrisburg.

Jul 2025“Relative Correlations, Not Initial States, Govern Positivity in Open Quantum Dynamics,” Quantum Gravity 2025, Institute for Gravitation & the Cosmos, Penn State.

Oct 2025“Open Quantum Systems via Dynamical Maps,” Primordial Universe & Gravity Seminar, IGC, Penn State.

Sep 2024“Open Quantum Systems via Dynamical Maps,” Colloquium, Department of Physics & Astronomy, San José State University.

A full list of talks and posters, including the “Entropy Whisperer” poster award (University of Rochester, 2026), is in the CV.

Honors & Awards

2026“Entropy Whisperer” poster award, University of Rochester

2024–2026W. Donald Miller Graduate Fellowship, Penn State

2024–2025David C. Duncan Graduate Fellowship, Penn State

2022–2025Verne M. Willaman Distinguished Graduate Fellowship, Penn State

2024NSF Graduate Research Fellowship, Honorable Mention

2022–2023Nellie H. and Oscar L. Roberts Graduate Fellowship, Penn State