Eric J. Sung

Applied Mathematics PhD student working at the intersection of condensed matter theory, open quantum systems, and analog gravity.

Created:   Updated:

Note: I primarily publish under Eric J. Sung. However, some of my (earlier) works are published under Junhyup Sung.

Research Interests

Condensed Matter Physics, Nonequilibrium Quantum Many-Body Physics, Scientific Machine Learning, General Relativity

Publications

  1. E. J. Sung, A. G. Campos, H. Abele, and D. I. Bondar, Decoherence-Free Entropic Gravity for a Dirac Fermion, Physical Review D 108, 104036 (2023).
    DOI
    Abstract
    The theory of entropic gravity conjectures that gravity emerges thermodynamically rather than being a fundamental force. One of the main criticisms of entropic gravity is that it would lead to quantum massive particles losing coherence in free fall, which is not observed experimentally. This criticism was refuted in Schimmoller et al. [Phys. Rev. Res. 3, 033065 (2021)], where a nonrelativistic master equation modeling gravity as an open quantum system interaction demonstrated that in the strong coupling limit, coherence could be maintained and reproduce conventional free-fall dynamics. Moreover, the nonrelativistic master equation was shown to be fully compatible with the qbounce experiment for ultracold neutrons. Motivated by this, we extend these results to gravitationally accelerating Dirac fermions. We achieve this by using the Dirac equation in Rindler space and modeling entropic gravity as a thermal bath thus adopting the open quantum systems approach as well. We demonstrate that in the strong coupling limit, our entropic gravity model maintains quantum coherence for Dirac fermions. In addition, we demonstrate that spin is not affected by entropic gravity. We use the Foldy-Wouthysen transformation to demonstrate that it reduces to the nonrelativistic master equation, supporting the entropic gravity hypothesis for Dirac fermions. Also, we demonstrate how antigravity seemingly arises from the Dirac equation for free-falling antiparticles but use numerical simulations to show that this phenomenon originates from zitterbewegung thus not violating the equivalence principle.
    BibTeX
    BibTeX citation 
    @article{sungDecoherencefreeEntropicGravity2023,
  title = {Decoherence-Free Entropic Gravity for a {{Dirac}} Fermion},
  author = {Sung, Eric J. and Campos, Andre G. and Abele, Hartmut and Bondar, Denys I.},
  journal = {Physical Review D},
  year = {2023},
  month = {nov},
  volume = {108},
  number = {10},
  pages = {104036},
  publisher = {American Physical Society},
  doi = {10.1103/PhysRevD.108.104036}
}

Under Review

  1. E. J. Sung and C. A. Stafford, Decoherence and the Reemergence of Coherence From a Superconducting "Horizon", (2026).
    arXiv
    Abstract
    In a recent paper [arXiv:2205.06279], Danielson et al. demonstrated that the mere presence of a black hole causes universal decoherence of quantum superpositions (dubbed the DSW decoherence). We analyze decoherence in a superconducting analogue [arXiv:1709.06154] of the event horizon of a late-stage black hole, where Andreev reflection plays the role of Hawking radiation. We consider a normal metal interferometer threaded by an Aharonov-Bohm flux, where one of the arms of the interferometer is coupled to a superconductor by a tunnel coupling of varying strength. At absolute zero temperature and for weak coupling, we find that the scattering states of the interferometer are decohered by Andreev reflection, a nontrivial manifestation of the proximity effect analogous to DSW decoherence from the event horizon of a black hole. However, for increasing coupling strength to the superconductor, we find a reemergence of coherence via resonant tunneling through Andreev bound states. This suggests the existence of an analogue gravitational phenomenon wherein transmission mediated by virtual Hawking radiation leads to a reemergence of coherence in an interferometer placed near a black hole’s event horizon.
    BibTeX
    BibTeX citation 
    @misc{sungDecoherenceReemergenceCoherence2026,
  title = {Decoherence and the {{Reemergence}} of {{Coherence From}} a {{Superconducting}} "{{Horizon}}"},
  author = {Sung, Eric J. and Stafford, Charles A.},
  year = {2026},
  month = {nov},
  number = {arXiv:2603.16765},
  publisher = {arXiv},
  doi = {10.48550/arXiv.2603.16765},
  eprint = {2603.16765},
  archiveprefix = {arXiv},
  primaryclass = {quant-ph}
}
  2. E. J. Sung, B. Koch, T. Jenke, H. Abele, and D. I. Bondar, Generalized Boundary Conditions for the qBounce Experiment, (2025).
    arXiv
    Abstract
    Discrepancies between theory and recent qBounce data have prompted renewed scrutiny of how boundary conditions are implemented for ultracold neutrons bouncing above a mirror in Earth’s gravity. We apply the theory of self-adjoint extensions to the linear gravitational potential on the half-line and derive the most general boundary condition that renders the Hamiltonian self-adjoint. This introduces a single real self-adjoint parameter \λthat continuously interpolates between the Dirichlet case and more general (Robin-type) reflecting surfaces. Building on this framework, we provide analytical expressions for the energy spectrum, eigenfunctions, relevant matrix elements, and a set of sum rules valid for arbitrary \λ\. We show how nontrivial boundary conditions can bias measurements of \g and can mimic or mask putative short-range ”fifth-force”. Our results emphasize that enforcing self-adjointness-and modeling the correct boundary physics-is essential for quantitative predictions in gravitational quantum states. Beyond neutron quantum bounces, the approach is broadly applicable to systems where boundaries and self-adjointness govern the observable spectra and dynamics.
    BibTeX
    BibTeX citation 
    @misc{sungGeneralizedBoundaryConditions2025,
  title = {Generalized {{Boundary Conditions}} for the {{qBounce Experiment}}},
  author = {Sung, Eric J. and Koch, Benjamin and Jenke, Tobias and Abele, Hartmut and Bondar, Denys I.},
  year = {2025},
  month = {oct},
  number = {arXiv:2510.15341},
  publisher = {arXiv},
  doi = {10.48550/arXiv.2510.15341},
  eprint = {2510.15341},
  archiveprefix = {arXiv},
  primaryclass = {quant-ph}
}

Conference Presentations and Abstracts

  1. C. A. Stafford and E. J. Sung, Decoherence from a Superconducting "Horizon", in APS Meetings Archive (Denver, Colorado, 2026).
    Abstract
    In a recent paper [1], Danielson et al. demonstrated that the mere presence of a black hole causes universal decoherence of quantum superpositions (dubbed the DSW decoherence) within a finite amount of time. This result has profound implications for the interplay of quantum mechanics and gravity. We analyze decoherence in a superconducting analog [2] of the event horizon of a black hole, where Andreev reflection plays the role of Hawking radiation. We consider a normal metal interferometer threaded by an Aharonov-Bohm flux, where one of the arms of the interferometer is coupled to a supercondutor by a normal metal bridge of varying length. At absolute zero, we find that the scattering states of the interferometer are decohered by Andreev reflection, a nontrivial manifestation of the proximity effect analogous to DSW decoherence from the event horizon of a black hole. Various metrics for decoherence are considered and the dependence on the distance of the SN interface to the interferometer is analyzed. Our results open a new path to study black hole quantum physics on earth via analog studies.[1] D. L. Danielson, G. Satishchandran, and R. M. Wald, “Black holes decohere quantum superpositions”, International Journal of Modern Physics D 31, 2241003 (2022).[2] S. K. Manikandan and A. N. Jordan, “Andreev reflections and the quantum physics of black holes”, Physical Review D 96, 124011 (2017).
    BibTeX
    BibTeX citation 
    @inproceedings{staffordDecoherenceSuperconductingHorizon2026,
  title = {Decoherence from a Superconducting "Horizon"},
  author = {Stafford, Charles A. and Sung, Eric J.},
  booktitle = {{{APS Meetings Archive}}},
  year = {2026},
  month = {mar},
  address = {Denver, Colorado}
}
  2. J. Sung, B. Crooke, D. Carstens, C. Woock, R. Amer, and A. Kolker, Sentinel-1A InSAR Time Series Analysis for Monitoring of Surface Subsidence in Coastal Louisiana, in AGU Fall Meeting Abstracts, Vol. 2018 (2018), pp. G21C-0571.
    Abstract
    While it is well known that coastal Louisiana is subsiding at one of the most rapid rates in the world today, much less is known about the spatial and temporal variability in subsidence rates and the causes of this variability. This is a critical knowledge gap because subsidence amplifies sea level rise and vast areas of the Louisiana coastal zone are currently at risk from rising relative sea-levels that threaten the health of coastal wetlands, adversely affect the stability of levees, roads and bridges, and increase flood risks to homes and communities. This collaborative project is expanding on the limited amount of knowledge about subsidence in coastal Louisiana using a combination of geophysical methods. This project combines the Interferometric Synthetic Aperture Radar (InSAR) remote sensing data with Real Time Kinetic (RTK) GPS data for measuring and improving the accuracy and spatial precision of the subsidence rates in the Lafourche transect of the Louisiana coastal zone. SAR time series images from February 2017 to January 2018 acquired by the comparatively new satellite Sentinel-1A of the European Space Agency (ESA). InSAR time series have been calculated on the ascending scenes using the Small Baseline Subset (SBAS) method. The preliminary results obtained indicate the efficiency of Sentinel-1A in monitoring land surface subsidence. The estimated subsidence rate ranges from 0.2 - 1.64 cm/yr. Nearly 100 RTK GPS points were collected in July 2018 to create an updated elevation database of specific locations in the Lafourche transect of the Louisiana coastal zone to calculate the rate of subsidence and evaluate the results of Sentinel-1A. InSAR time series will be calculated from Sentinel-1A ascending images for 2019. Another set of RTK GPS points will be collected in July 2019 for ground truthing and evaluation of InSAR results. Geographic Information Systems (GIS) are being used to compare subsidence rates with soil types, water level changes, land use and land cover changes. This project will provide an improved understanding of subsidence rates using advanced remote sensing technologies, which will likely identify infrastructure at risk from its location over subsidence in Coastal Louisiana.
    BibTeX
    BibTeX citation 
    @inproceedings{sungSentinel1AInSARTime2018,
  title = {Sentinel-{{1A InSAR Time Series Analysis}} for {{Monitoring}} of {{Surface Subsidence}} in {{Coastal Louisiana}}},
  author = {Sung, J. and Crooke, B. and Carstens, D. and Woock, C. and Amer, R. and Kolker, A.},
  booktitle = {{{AGU Fall Meeting Abstracts}}},
  year = {2018},
  month = {dec},
  volume = {2018},
  pages = {G21C-0571}
}

Conferences and Workshops Attended

  • 2026 MSTIC Summer Symposium (Talk), Aug 2026. Sandia National Laboratories, Albuquerque, NM.
  • Quantum Thermodynamics & Decoherence (QTD) Symposium 2026 (Poster), Jun 2026. University of Rochester, Rochester, NY.
  • American Physical Society Global Physics Summit 2026 (Talk), Mar 2026. Denver, CO.
  • Math for All in New Orleans, Mar 2020. Tulane University, New Orleans, LA.
  • Clifford Lectures, Oct 2019. Tulane University, New Orleans, LA.
  • 2018 American Geophysical Union (AGU) Fall Meeting (Poster), Dec 2018. Washington, DC.

Master’s Thesis

Mathematics and Applications of Feynman Diagrams
Thesis Advisor: Prof. Victor H. Moll

Undergraduate Senior Seminar Paper

Mathematical Fluid Dynamics of Microorganisms
Seminar Advisor: Prof. Lisa J. Fauci