Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session K72: Entanglement and Entropy for Multiparty Quantum Systems |
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Sponsoring Units: DQI Chair: Tony Jin, University of Chicago Room: Room 406 |
Tuesday, March 7, 2023 3:00PM - 3:12PM |
K72.00001: Entanglement area law for 1D gauge theories and bosonic systems Yu Tong, Yuan Su, Nilin Abrahamsen, Nathan Wiebe, Ning Bao In this talk I will introduce the proof of an entanglement area law for a class of 1D quantum systems involving infinite-dimensional local Hilbert spaces. This class of quantum systems include bosonic models and lattice gauge theories in one spatial dimension. Our proof relies on new results concerning the robustness of the ground state and spectral gap to the truncation of Hilbert space, applied within the approximate ground state projector (AGSP) framework. Our result provides theoretical justification for using tensor networks to study the ground state properties of quantum systems with infinite local degrees of freedom. |
Tuesday, March 7, 2023 3:12PM - 3:24PM |
K72.00002: Multipartite entanglement in the random Ising chain Jay S Zou, Istvan A Kovacs, Helen S Ansell Quantum entanglement is a distinguishing property that offers fundamentally stronger correlations than classical physics. Entanglement of a single subsystem is well understood through entanglement entropy, showing a term known as the "area law" and a logarithmic term with a universal prefactor that is unique at quantum phase transitions. However, quantifying entanglement across multiple subsystems is a challenging open problem in interacting quantum systems. Here, we consider two subsystems of length l separated by a distance r and quantify two measures of multipartite quantum correlations, entanglement negativity (?) and mutual information (Ι), in critical random Ising chains. The ground states of the random Ising chains are generated through the asymptotically exact strong disorder renormalization group method. By relating ? and Ι to a cluster counting problem and though numerical simulations, we find universal constants of ? and Ι over any distances when r = αl. |
Tuesday, March 7, 2023 3:24PM - 3:36PM |
K72.00003: Momentum Space Entanglement from the Wilsonian Effective Action Matheus H Martins Costa The entanglement between momentum modes of a quantum field theory at different scales is not as well studied as its counterpart in real space, despite the natural connection with the Wilsonian idea of integrating out the high-momentum degrees of freedom. We push such a connection further by developing a novel method to calculate the Rényi and entanglement entropies between slow and fast modes, which is based on the Wilsonian effective action at a given scale. This procedure is applied to the perturbative regime of some scalar theories, comparing the lowest-order results with those from the literature and interpreting them in terms of Feynman diagrams. Our method is also easily generalized to higher-order or nonperturbative calculationsa and it has the advantage of avoiding the matrix diagonalizations of other techniques. Finally, we also use a quantum information point of view of the renormalization group to derive a remarkable property of theories at a RG fixed point: they have no entanglement between momentum scales. Our results pave the way for further exploring the relation between renormalization and entanglement, including the role played by the latter in determining the phase structure of the underlying theories. |
Tuesday, March 7, 2023 3:36PM - 3:48PM |
K72.00004: Entanglement degradation in bipartite systems with a finite-lifetime observer Pablo A Lopez-Duque, Abhijit Chakraborty, Carlos R Ordonez, Horacio E Camblong A bipartite system composed by an inertial observer (Alice) and an accelerated observer (Charlie) has been used in previous studies to show a connection between entanglement degradation and the Unruh effect. The degradation in entanglement between two modes of a non-interacting scalar field is attributed to the relative acceleration between the observers. In this work, we analyze the influence of an observer finite lifetime in the entanglement of a bipartite system where the other observer is inertial. The finite lifetime observer is restricted to move in a causal diamond, which helps establish a connection with the constantly accelerated observer case. The system is initially in a maximally entangled state, observed form the perspective of inertial observers, and it becomes less entangled as the lifetime shortens. We argue that this effect is due to the presence of the causal horizons. |
Tuesday, March 7, 2023 3:48PM - 4:00PM |
K72.00005: Quantum-engineered Superradiant Phase Transition in the Strong Coupling Regime Jin-Feng Huang, Lin Tian The standard Dicke model can exhibit quantum phase transition between the normal and the superradiant phases with macroscopic excitations in the cavity and the qubits when the strength of the light-matter coupling exceeds the ultrastrong coupling regime. However, it is challenging to observe this phase transition in practical systems due to limited coupling strengths or finite two-photon terms in the system. In this work we show that by applying a periodic modulation to the frequency of the two-level systems in a standard Dicke model in the strong coupling regime, where the coupling strength is much less than the qubit and cavity frequencies, an anisotropic Dicke model with tunable rotating and counter-rotating terms in the ultrastrong coupling regime can be achieved. We calculate the ground state and the excitation spectrum of this model in terms of the modulation parameters. Our result shows that the superradiant phases can be observed in cavity- or circuit-quantum electrodynamics systems with only strong coupling. |
Tuesday, March 7, 2023 4:00PM - 4:12PM |
K72.00006: Deconfinement and Error Thresholds in Holography ChunJun (Charles) Cao, Ning Bao, Guanyu Zhu We study the error threshold properties of holographic quantum error-correcting codes in the context of the AdS/CFT correspondence. We demonstrate that holographic conformal field theories admit an algebraic threshold, which is related to the confinement-deconfinement phase transition. We then apply geometric intuition from holography and the Hawking-Page phase transition to motivate the conformal field theory result, and comment on potential extensions to other confining theories. In particular, we show that the corruption of logical information above the threshold can be seen as information being engulfed by a black hole in the dual holographic spacetime in one higher dimension. |
Tuesday, March 7, 2023 4:12PM - 4:24PM |
K72.00007: Design Constraints on a Unruh-DeWitt Quantum Computer. Eric W Aspling A quantum computer that utilizes both stationary qubits, as well as flying qubits could provide new insights into quantum computing as well as quantum materials. Well-known and experimentally verified condensed matter systems, such as Luttinger liquids utilizing fermionic edge states, coupled to spin qubits create a quantum bus that performs all-to-all connected operations using stationary and flying qubits. Modeling the qubit-field interactions with Unruh-DeWitt detectors introduces novel quantum devices that offer promising results for computations that pass quantum information from one stationary qubit to another via flying qubit. To see this, we explore Relativistic Quantum Information theory, where there has been significant progress using scalar fields to evaluate quantum information passing onto and off of quantum fields in the regime of strong coupling, a requirement of quantum computing. However, there has been less progress with theories for strongly coupled Dirac fermions. Through bosonization, we show Unruh-DeWitt detectors can process quantum information on channels with near-perfect channel capacity and do so with fermionic Flying Qubits. Through theory and simulation, our results point the way toward the experimental study of quantum information in quantum fields via condensed matter physics. |
Tuesday, March 7, 2023 4:24PM - 4:36PM |
K72.00008: Quantum Reflection of Atoms from 2D Dirac Materials Sang Wook Kim, Mohamed M Elsayed, Adrian G Del Maestro, Valeri N Kotov We show that quantum reflection (QR) from two-dimensional (2D) Dirac materials, such as graphene-based structures, can simultaneously serve as a sensitive probe of the fundamental van der Waals (VDW) / Casimir interaction as well as the 2D material's quasiparticle energy. Attractive atom—2D material potential tails are strongly dependent on material characteristics. We find that applying mechanical strain, introducing carrier doping, or tuning the energy gap by considering different 2D materials, have a profound effect on the QR coefficient. In addition to atoms interacting with graphene in various configurations, we have analyzed the 2D family of semiconducting dichalcogenides. Overall we conclude that quantum reflection phenomena make 2D quantum materials an attractive platform for studies of many-body physics involving atoms near solid-state environments. |
Tuesday, March 7, 2023 4:36PM - 4:48PM |
K72.00009: Microwave spectroscopy of interacting Andreev spins Jaap J Wesdorp, Francisco Matute-Cañadas, Arjen Vaartjes, Lukas Gruenhaupt, Tom Laeven, Sebastiaan Roelofs, Lukas Johannes Splitthoff, Marta Pita-Vidal, Arno Bargerbos, David J Van Woerkom, Peter Krogstrup, Leo P Kouwenhoven, Christian K Andersen, Alfredo Levy Yeyati, Bernard Van Heck, Gijs de Lange Andreev bound states are fermionic states localized in weak links between superconductors which |
Tuesday, March 7, 2023 4:48PM - 5:00PM |
K72.00010: Coherence time for spin defects at aqueous interfaces Alfonso Castillo, Mykyta Onizhuk, Giulia Galli Spin defects in two-dimensional (2D) materials are strong candidates for quantum information technology applications, in particular quantum sensing. Compared with thin films of 3D solids, 2D layers are free from unsaturated surface dangling bonds, which are detrimental to spin coherence. Interestingly, recent theoretical studies predicted a significant increase in the coherence time of defect-based qubits in monolayers, compared to their bulk counterparts [1,2]. In this work, we computed coherence times of spin defects in 2D materials in contact with water, geared towards understanding quantum sensors for biological systems. We consider graphene and hexagonal boron nitride (hBN) layers as test systems. We generated a structural model of the layer/water interface by performing classical molecular dynamics (MD) simulations of confined water between two graphene/hBN sheets using the LAMMPS code. We then used the MD trajectories to generate spin bath configurations for hypothetical spin defects in the solid layer, using the cluster correlation expansion method and the PyCCE code [3]. We considered an NV-like spin defect in graphene and a negatively charged boron-vacancy in hBN. In this talk we discuss how coherence time of defects in these two-dimensional materials in contact with water depend on magnetic field strength, nuclear spin concentration and isotopic composition. |
Tuesday, March 7, 2023 5:00PM - 5:12PM |
K72.00011: Efficient simulation of rotation-symmetric many-boson open quantum systems via symmetric time-dependent variational ansatz David S Schlegel, Fabrizio Minganti, Vincenzo Savona The efficient simulation of the open-quantum-system dynamics of many interacting bosons is a key requirement for the design of optimal bosonic error-correcting codes and for predicting their performance when subject to noise. In most cases, this however constitutes a daunting computational challenge due to the prohibitively large Hilbert space. Bosonic codes always rely on symmetries and, within typical quantum protocols, their dynamics is constrained onto narrow corners of the full state space. Here, we present a new paradigm for the simulation of $Z_N$-rotation symmetric many-boson driven-dissipative systems -- i.e. Schrödinger cat codes -- based on a self-consistent multicomponent coherent-state expansion. The method relies on a variational ansatz for the $n$-boson density matrix expressed on a coherent-state subspace, where both the matrix elements and the coherent-state displacement field constitute the time-dependent variational parameters. This method efficiently represents the system dynamics while retaining only the computational complexity of an equivalent $n$-qubit quantum state evolution. We test our model on several examples, demonstrating its potential application to the predictive simulation of the most advanced bosonic codes. |
Tuesday, March 7, 2023 5:12PM - 5:24PM |
K72.00012: The X-Cube Floquet Code Zhehao Zhang, David Aasen, Sagar Vijay Inspired by the coupled-layer construction of the X-Cube model, we introduce the X-Cube Floquet code. The X-Cube Floquet code is defined on a three-dimensional lattice, built from intersecting 4.8.8 lattice layers in the $xy$, $yz$, and $xz$ directions. It consists of a period sequence of two-qubit measurements including both intra-layer and inter-layer measurements. Within a single Floquet cycle, the codespace switches between that of the X-Cube model and layers of entangled, two-dimensional toric codes, as a consequence of the coupled-layers construction. The encoded logical qubits' dynamics are analyzed, and we argue that the new code has a non-zero error threshold. We provide a new Hamiltonian realization of the X-Cube model and, more generally, explore the phase diagram related to the sequence of measurements that define the X-Cube Floquet code. |
Tuesday, March 7, 2023 5:24PM - 5:36PM |
K72.00013: Large-scale on-chip integration of hybrid gate-voltage addressable semiconducting quantum wells field effect nano-switch array in superconducting circuits Kaveh Delfanazari, Jiahui Li, YUSHENG XIONG, Peng Ma, Reuben Puddy, Ian Farrer, Sachio Komori, Jason Robinson, Llorenç Serra, David A Ritchie, Michael J Kelly, Hannah Joyce, Charles G Smith We experimentally demonstrate a novel realisation of scalable, addressable, and gate voltage controllable hybrid field-effect quantum chips. Each chip contains arrays of split gate hybrid junctions made from InGaAs quantum wells integrated with superconducting circuits. Each hybrid junction in the chip can be addressed through its corresponding source-drain as well as two global split gate contact pads that allow switching between (super)conducting and insulating states. We investigate the electrical response of 18 fabricated chips with a total of 144 field-effect hybrid Nb-2DEG-Nb quantum devices at cryogenic temperatures and study their switching voltage (on/off) statistics, quantum yield, and reproducibility. Our approach paves the way for the novel realisation of scalable cryogenic electronic hardware at chip scale essential for applications in classical-quantum technologies. |
Tuesday, March 7, 2023 5:36PM - 5:48PM |
K72.00014: A Model for Quantum Autonomous Boolean Networks Ian T Durham Autonomous Boolean networks were first developed in the late 1960s as a tool for studying evolvability in complex systems. Notably Kauffman's NK model proved to be particularly useful for understanding genetic regulatory systems. It wasn't until the early 2000s that more extensive mathematical studies of these networks were undertaken and, while the NK model has been applied to a handful of quantum systems, a direct quantum analog has not been developed. In this work we develop just such a quantum model. In particular we focus on Boolean functions of two logical inputs. Due to requirements of unitarity, some functions require an additional ancilla qubit. As in Kauffman's model the network connections are chosen randomly and then set. While the quantum network evolves deterministically (as long as there is no measurement) and thus exhibits state cycles, unlike the classical state cycles, the length of the quantum state cycles appears to be independent of the number of nodes in the network and the lengths vary considerably. These networks also exhibit a cyclic entanglement structure. While these networks can reproduce the classical structures discovered by Kauffman when limited to purely classical inputs, they exhibit a much richer landscape of structure when extended to the quantum regime. We also explore the robustness of these networks to small perturbations and we show that, like their classical counterparts, they exhibit clustering phenomena. |
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