SESSION 9c: Explorations in quantum information theory -- Sousa/Joplin/Seeger

Chair: (Christopher Jackson (University of New Mexico))
3:45pm - 4:15pmPeter J. Love, Tufts University
Simulating quantum field theory in the light-front formulation
Abstract. We explore the possibility of simulating relativistic field theories in the light-front (LF) formulation and argue that such a framework has numerous advantages as compared to both lattice and second-quantized equal-time approaches. These include a small number of physical degrees of freedom leading to reduced resource requirements, efficient encoding with model-independent asymptotics, and sparse Hamiltonians. Many quantities of physical interest are naturally defined in the LF, resulting in simple measurements. The LF formulation allows one to trace the connection between relativistic field theories and quantum chemistry, thus permitting to use numerous techniques developed in the last decade. It also provides a promising application for NISQ devices, since for certain calculations one may need of an order of hundred qubits. As an example, we provide a detailed algorithm for calculating analogues of QCD parton distribution functions in a simple 1+1-dimensional model. We also discuss the generalization to QCD, and provide estimates.
4:15pm - 4:45pmSepehr Nezami, California Institute of Technology
Quantum gravity in the lab: teleportation by size and traversable wormholes
Abstract. Traversable wormholes in holography exhibit a strange phenomenon: with the aid of a simple and weak coupling, any local signal inserted at time −t in one boundary system -followed by the dissipation caused by chaotic dynamics- reappears at time +t on the other boundary system. Inspired by the traversable wormholes, we propose teleportation experiments that can readily be performed in an atomic physics lab exhibiting similar behavior. We study this phenomenon when the entanglement between two systems is maximal (i.e., infinite temperature thermofield double (TFD) state) in various systems. We introduce the core information theoretic paradigm behind this phenomenon, which we call Teleportation by Size, to encapsulate how the physics of operator size growth naturally leads to transmission of a signal in many different scenarios. We argue that the infinite temperature phenomenon, although sharing the surprising properties, does not immediately correspond to a signal going through a wormhole. In fact, in the systems with gravitational dual, this corresponds to transmission of signal with the aid of vastly different geometries. Instead, we introduce a property of the growth distribution of operators called size winding, which only exists at low temperature, and show that it explains the boundary physics of the signals traversing in geometrical wormholes. We argue that an imperfect form of size winding -common in quantum systems- has an imprint on the fidelity of teleportation.
4:45pm - 5:15pmChris Sutherland, University of Southern California
Non-Markovianity of the post-Markovian master equation
Abstract. An easily solvable quantum master equation has long been sought that takes into account memory effects induced on the system by the bath, i.e., non-Markovian effects. We briefly review the post-Markovian master equation (PMME), which is relatively easy to solve, and analyze a simple example where solutions obtained exhibit non-Markovianity. We apply the distinguishability measure introduced by Breuer et al., and we also explicitly analyze the divisibility of the associated quantum dynamical maps. We give a mathematical condition on the memory kernel used in the PMME that guarantees non-CP-divisible dynamics.
5:15pm - 5:45pmTzula Propp, University of Oregon
Limits to single photon detection: Amplification
Abstract. We have constructed a model of photo detection that is both idealized and realistic enough to calculate the limits and tradeoffs inherent to single photon detector (SPD) figures of merit. This model consists of three parts: transmission, amplification, and measurement. In this talk, we discuss the effects of signal amplification post-filtering; by first writing correct commutator-preserving transformations for non-linear photon-number amplification (e.g. avalanche photodiode, electron-hole pair creation, electron shelving), we derive alternative noise limits that out- perform the well-known Caves limits for linear amplification of bosonic mode amplitudes and possess no zero-temperature noise contribution to boson number SNR. We then discuss the optimistic implications for single photon detection. Lastly, we briefly discuss the pre-amplification filtering process (transmission) along with the construction of POVMs completely describing photo detectors (measurement), from which one can calculate all standard SPD figures of merit.
5:45pm - 6:15pmPaolo Zanardi, University of Southern California
Quantifying the incompatibility of quantum measurements Relative to a Basis
Abstract. Motivated by quantum resource theories, we introduce a notion of incompatibility for quantum measurements relative to a reference basis. The notion arises by considering states diagonal in that basis and investigating whether probability distributions associated with different quantum measurements can be converted into one another by probabilistic postprocessing. The induced preorder over quantum measurements is directly related to multivariate majorization and gives rise to families of monotones, i.e., scalar quantifiers that preserve the ordering. For the case of orthogonal measurement we establish a quantitative connection between incompatibility, quantum coherence and entropic uncertainty relations. We generalize the construction to include arbitrary positive-operator-valued measurements and report complete families of monotones

SQuInT Chief Organizer
Akimasa Miyake, Associate Professor

SQuInT Co-Organizer
Brian Smith, Associate Professor UO

SQuInT Program Committee
Postdoctoral Fellows:
Markus Allgaier (UO OMQ)
Sayonee Ray (UNM CQuIC)
Pablo Poggi (UNM CQuIC)
Valerian Thiel (UO OMQ)

SQuInT Event Co-Organizers (Oregon)
Jorjie Arden
Holly Lynn

SQuInT Event Administrator (Oregon)
Brandy Todd

SQuInT Administrator (CQuIC)
Gloria Cordova
505 277-1850

SQuInT Founder
Ivan Deutsch, Regents' Professor, CQuIC Director

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