Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session W35: General Quantum Information IVRecordings Available

Hide Abstracts 
Sponsoring Units: DQI Chair: Peter Maurer, University of Chicago Room: McCormick Place W193B 
Thursday, March 17, 2022 3:00PM  3:12PM 
W35.00001: Selftesting quantum state and apparatus in embedded system Abu Ashik Md. Irfan, Gerardo Ortiz Deviceindependent certification of quantum apparatus and quantum state has essential application in Quantum Communication and Quantum Computing. A stringent approach to certification is Quantum selftesting protocol, where minimum assumptions regarding the system and apparatus are taken into account; the only assumption is the compatibilities between observables. While there is significant progress in applying such kind protocol for the case of quantum communication, the literature for the case of quantum computing is limited. Our focus is the certifications of operators and states in different quantum computing systems, including topological qubits, cold atom, ion trap, etc., where qubits are not necessarily spacelike separated. Regarding these kinds of systems, one can be skeptical and question the existence of entanglement between subsystems, or they want to characterize the measurement observables' fidelities. Quantum selftesting can help in this regard. We are adapting the protocols that are used in QKD and applying them to these cases. Currently, we are deriving the protocols which can calculate state and operator fidelities of these kinds of systems. 
Thursday, March 17, 2022 3:12PM  3:24PM 
W35.00002: Hilbert space fragmentation produces a "fracton Casimir effect" Xiaozhou Feng, Brian Skinner Fracton systems exhibit restricted mobility of their excitations due to the presence of higherorder conservation laws. Here we study the time evolution of a onedimensional fracton system with charge and dipole moment conservation using a random unitary circuit description. Previous work has shown that when unitary operators act on only three sites, the system fails to thermalize due to strong "fragmentation" of the Hilbert space. We show that threesite gate dynamics causes an effective attraction between isolated fractons or between a single fracton and the boundaries of the system, in analogy with the Casimir effect in quantum electrodynamics. We show how this attraction can be understood by exact mapping to a simple classical statistical mechanics problem, which we solve exactly for the case of an initial state with either one or two fractons. 
Thursday, March 17, 2022 3:24PM  3:36PM 
W35.00003: PetzRenyi Relative Entropy of Quantum Guassian States Tiju Cherian John We study the PetzRenyi αrelative entropy (PRRE) of quantum gaussian states with an emphasis to the infinite mode case and α>1. A formula to compute the PRRE of gaussian states both in the finite and infinite mode case is proved. Our approach provides a complete description of the PRRE of gaussian states which are tensor product of 1mode states and determines the interval of α for which the entropy is finite. This is a joint work is George Androulakis. 
Thursday, March 17, 2022 3:36PM  3:48PM 
W35.00004: A Quantum Measurement Engine and the Demon's Arrow of Time KAGAN YANIK, Sreenath K Manikandan, Andrew N Jordan, Bibek Bhandari We discuss a quantum measurement engine, powered by dichotomous quantum weak measurements on a single qubit weakly coupled to a thermal reservoir, and feedback controlled by a quantum Maxwell's demon. For a demon acquiring information via quantum weak measurements, we find that the work extracted can be associated with the demon's quantum measurement arrow of time. We also discuss a realistic timecontinuous operation of the engine where the measurement and feedback operations are timecontinuous. In addition, we show that the engine approaches a steady state for long enough time where it operates with finite efficiency. 
Thursday, March 17, 2022 3:48PM  4:00PM 
W35.00005: Quantum Information of Interference in Quantum Transport Justin P Bergfield Under thermal bias certain quantum coherent conductors exhibit local temperature oscillations where quantum interference mimics the actions of a Maxwell Demon, allowing the position of a temperature probe do selectively dictate whether electrons can tunnel from the hot or cold electrode. The quantum interference therefore encodes `which way` information about the path of the electron and encodes information. We investigate the information content of destructive quantum interference features (nodes) in the transport spectrum of singlemolecule junctions; systems composed of small organic molecules coupled to macroscopic electrodes and which have experimental evidence of possessing nodes. The importance of manybody correlations and dephasing are discussed. 
Thursday, March 17, 2022 4:00PM  4:12PM 
W35.00006: Szilardlike quantum heat engines in finite time Debmalya Das, George Thomas, Jukka P Pekola, Andrew N Jordan In a quantum Szilard engine, a contribution towards the net extracted work originates from the reorientation of the energyspectrum during insertion and removal of a potential barrier. In more practical experimental situations, the process of insertion or removal of the barrier is not adiabatic. Using numerical simulations, we explore the process of insertion of the potential barrier at various rates, taking the interaction with a thermal bath into consideration and the corresponding work required is calculated in the process. We show that in the case of very slow insertion, this work asymptotically approaches the adiabatic limit. We also discuss Szilard and Stirlinglike quantum heat engines operating in finitetime using this understanding. 
Thursday, March 17, 2022 4:12PM  4:24PM 
W35.00007: Late time von Neumann entropy and its transition Shaokai Jian, Brian Swingle We study the latetime entanglement entropy and its transition in monitored Brownian SYK chains in the largeN limit. Without measurement the steady state nth Renyi entropy is obtained by summing over a class of solutions, and is found to saturate to the Page value in the n=1 limit. In the presence of measurements, the analytical continuation n=1 is performed using the cyclic symmetric solution. The result shows that as the monitoring rate increases, a continuous von Neumann entanglement entropy transition from volumelaw to arealaw occurs at the point of replica symmetry unbreaking. 
Thursday, March 17, 2022 4:24PM  4:36PM 
W35.00008: Postselection and Quantum Energetics Spencer C Rogers, Andrew N Jordan When an unread measurement of an energynoncommuting property causes the mean energy of a system to change, the measurement apparatus's mean energy change should be equal and opposite. How this balance works out when we postselect on a particular measurement outcome is less obvious. Then the shift of the energy of the measurement apparatus is similar to a weak value, since energy conservation weakly correlates the energies of the apparatus and measured system. We calculate this shift for a realistic qubit measurement protocol involving coupling to an oscillator. We show that this shift depends on the particular form of the coupling interaction: for the same target qubit dynamics, a JaynesCummings interaction gives different results from a similar interaction with advantageous degeneracies. For the latter interaction type, we give a formula for the conditional mean energy shift of the measurement apparatus, in terms of qubit properties, including the energy weak value. This formula has intuitive consequences, particularly when the qubit is prepared in an energy eigenstate. The JaynesCummings interaction, by contrast, has surprising experimental effects. 
Thursday, March 17, 2022 4:36PM  4:48PM 
W35.00009: Approximating a LowDimensional Nonlinear Dual to the Schrödinger Equation Using Neural Networks Huston R Wilhite, Mark K Transtrum, JeanFrancois S Van Huele Unlike classical physics, where the physical systems evolve in a finitedimensional space and are typically nonlinear, quantum mechanics takes place in an infinitedimensional space where time evolution is linear. Koopman operator theory uses an infinite dimensional operator to evolve a finitedimensional, nonlinear dynamical system linearly in an infinitedimensional space. We conjecture that the Schrödinger equation can be represented as the Koopman operator of a finitedimensional system with nonlinear dynamics. Since the Koopman operator has no analytic inverse in general, we use neural networks to approximate the functions which convert the system from finitedimensional to infinitedimensional as well as the dynamics within the finitedimensional space. We treat the infinitedimensional quantum state space as observations on the finitedimensional space and learn a basis of observations for the quantum state space. We then learn the dynamics of the compressed states, which when observed in the quantum state space reproduce the dynamics of the Schrödinger equation. Based on preliminary results on a generic quantum system, we expect that this method will be effective at replicating the dynamics of quantum systems with continuous variables. 
Thursday, March 17, 2022 4:48PM  5:00PM 
W35.00010: Quantum Chaos is Quantum. Salvatore Francesco Emanuele Oliviero, Alioscia Hamma It is well known that a quantum circuit on nqubits composed of Clifford gates with the addition of k Tgates can be simulated on a classical computer by an algorithm scaling polynomially in n and an exponentially in k. Our work in this direction focused on finding the number of nonClifford resources needed to simulate quantum chaos. Can quantum chaos be efficiently simulated on a classical computer? In other words, how many nonClifford resources are required to simulate quantum chaotic bahavior? We proved that Θ(n) nonClifford resources are necessary to access full quantum chaotic behavior, and this reflects the impossibility of simulating quantum chaos on a classical computer: quantum chaos is quantum. 
Thursday, March 17, 2022 5:00PM  5:12PM 
W35.00011: Quantum battery at the verge of a phase transition Felipe Barra When the equilibrium state of a system coupled to a bath is an athermal state, i.e., not of the Gibbs form ∽exp( βH), energy can be extracted from it in a unitary cyclic process. Starting from that observation, we introduce and study a batterycharger quantum device. The device operates in a cycle with four stages: the equilibrium storage stage is interrupted by disconnecting the battery from the charger, then work is extracted from the battery, and then the battery is reconnected with the charger; finally, the system is brought back to equilibrium. 
Thursday, March 17, 2022 5:12PM  5:24PM 
W35.00012: Quantum information with top quarks at the LHC Juan R Muñoz de Nova, Yoav Afik Due to its genuine relativistic behavior, exotic character of interactions and symmetries, and fundamental nature, highenergy colliders are attractive systems for the experimental study of fundamental aspects of quantum mechanics. We propose the detection of entanglement between the spins of topantitopquark pairs at the LHC, representing the first proposal of entanglement detection in a pair of quarks, and also the entanglement observation at the highest energy scale so far. We show that entanglement can be observed by direct measurement of the angular separation between the leptons arising from the decay of the topantitop pair. The detection can be achieved with high statistical significance, using the current data recorded during Run 2 at the LHC. In addition, we develop a simple protocol for the quantum tomography of the topantitop pair. This experimental reconstruction of the quantum state provides a new experimental tool to test theoretical predictions of New Physics beyond the Standard Model. Our work explicitly implements canonical experimental techniques in quantum information in a twoqubit highenergy system, paving the way to use highenergy colliders to also study quantum information theory. 
Thursday, March 17, 2022 5:24PM  5:36PM 
W35.00013: Using gravitational decoherence to constrain the number of extended quantum systems Harshit Verma, Magdalena Zych, Fabio Costa In the low energy regime, the effect of gravity on an evolving quantum system (clock) manifests as time dilation. A massive particle prepared in a spatial superposition near a composite particle with internal clocks decoheres due to entanglement between its spatial DOF and the states of the clocks. Here we expand this formalism to extended quantum systems (EQS) such as spin chains and construe the time dilation effect as a differential redshift of the local Hamiltonian along the chain, which depends on the relative position of the massive particle. Hence, at zero temperature, by the mere dependence of the ground state of the spin chain on the position of the gravitating particle, we establish gravitational decoherence caused by such an EQS. Since this effect is additive for many such independent EQS in the vicinity of a massive particle, we identify the number of spin chains that can cause detectable decoherence in the spatial superposition of the massive particle. The coherence observed in an experiment can, therefore, be used to put a fundamental limit on the number of EQS surrounding the spatial superposition of a massive particle. In principle, the method introduced here can be extended to quantum fields, putting a bound on the number of extant fundamental particles. 
Follow Us 
Engage
Become an APS Member 
My APS
Renew Membership 
Information for 
About APSThe American Physical Society (APS) is a nonprofit membership organization working to advance the knowledge of physics. 
© 2023 American Physical Society
 All rights reserved  Terms of Use
 Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 207403844
(301) 2093200
Editorial Office
1 Research Road, Ridge, NY 119612701
(631) 5914000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 200452001
(202) 6628700