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 A32: Nonequilibrium Dynamics in the Solid State |
Hide Abstracts |
Sponsoring Units: DCMP Chair: Yicheng Zhang, University of Oklahoma Room: Room 224 |
Monday, March 6, 2023 8:00AM - 8:12AM |
A32.00001: Observation of an excitonic state in a topological insulator Ryo Mori, Samuel T Ciocys, Kazuaki Takasan, Ping Ai, Kayla R Currier, Takahiro Morimoto, Joel E Moore, Alessandra Lanzara The exciton, a bound state of an electron and a hole, is a fundamental quasiparticle induced by coherent light-matter interactions in semiconductors. Recent progress of topological phases of matter has shed light on new routes to inducing novel excitonic phases. We will report a direct observation of the excitonic state in a topological insulator measured by the ultrafast technique and also discuss the results in terms of correlations. Our work opens up a new platform for exploring exciton-mediated state in topological materials and their application. |
Monday, March 6, 2023 8:12AM - 8:24AM |
A32.00002: Nonequilibrium dynamics in pumped excitonic insulators Satoshi Ejima Applying optical pulses on insulators provides us with a new route to realize an insulator-to-metal transition, which can be observed by time-resolved spectroscopy experiments. |
Monday, March 6, 2023 8:24AM - 8:36AM |
A32.00003: Light-Driven Transitions in Quantum Paraelectrics Premala Chandra, Ahana Chakraborty, Zekun Zhuang, Pavel Volkov, Piers Coleman Motivated by recent measurements of terahertz field-induced ferroelectric transitions in the quantum paraelectric SrTiO$_3$, we study a driven phonon system close to a second order phase transition. Exploring the system’s classical dynamics, we find that at sufficiently large fluence, there are polarization-sensitive transitions into ordered phases, some of which are inaccessible in equilibrium. More specifically for certain polarizations we demonstrate the existence of two-step transitions to ordered phases and at still higher fluence the onset of chaotic behavior. Moving beyond classical dynamics, we develop a formalism for including quantum corrections in a controlled way and we study the effects of quantum fluctuations on the critical fluences with observable consequences. |
Monday, March 6, 2023 8:36AM - 8:48AM |
A32.00004: Photocurrent induced by applying of bicircular light Yuya Ikeda Nonlinear optical responses in solids, including photovoltaic effect and harmonic generation, are physical phenomena triggered by intense light irradiation to materials. These are of great importance in studying the physics of excited states of the system as well as for applications to optical devices and solar cells. In particular, bulk photovoltaic effect (BPVE), namely DC photocurrents in response to uniform AC external fields, have attracted great attention as related to the Berry phase and the band topology of materials [1]. Here we propose the mechanism of a novel photocurrent induced by two-frequency drive with bicircular light (BCL), which can control the rotational symmetry of the system [2]. While ordinary second-order photocurrents can exist only in systems lacking inversion symmetry, BCL driving can induce photocurrents in materials with inversion or rotational symmetry. In particular, since BCL driving also breaks the time-reversal symmetry of the system, the photocurrent proportional to the relaxation time is dominant, called injection current. We show theoretically, using the Feynman diagrammatic method and the Keldysh-Floquet formalism, that BCL irradiation can produce third-order photocurrent and dynamically control the direction of the photocurrent. |
Monday, March 6, 2023 8:48AM - 9:00AM |
A32.00005: Photoinduced band renormalization effects in square-net materials Ioannis Petrides, Prineha Narang Out-of-equilibrium effects provide an elegant pathway for probing and understanding the underlying physics of correlated materials. In particular, controlling electronic band structure properties using ultrafast optical pulses has shown promise for creating exotic states of matter by inducing charge density waves, or modifying the fermi velocities of Dirac particles. Of recent interest is band renormalization effects in square-net materials as they possess interesting spectral properties, e.g., nodal lines or axial-Higgs physics. Here we present a theoretical study of out-of-equilibrium effects in the family of nodal line semimetals featuring a square net of atoms. Specifically, we show that the renormalization of the kinetic energy of electrons due to the ultrafast pump field leads to the enhancement of the effective mass and to the shift of the resonant frequencies of the material. Finally, we discuss signatures of such modifications in transient Rayleigh and Raman scattering. Our study demonstrates the potential of this approach in creating photoinduced phases in topological quantum matter through an all-optical route. |
Monday, March 6, 2023 9:00AM - 9:12AM |
A32.00006: Observation of ultrafast critical currents in optically-driven high-temperature K3C60 Eryin Wang, Joseph D Adelinia, Mariana Chavez Cervantes, Toru Matsuyama, Guido Meier, Andrea Cavalleri Most photo-induced functional phases observed quantum materials, which include non-equilibrium ferroelectricity [1], magnetism [2, 3], and superconductivity [4,5,6,7,8,9,10,11], have so far been characterized by measuring their transient optical properties. However, to probe new signatures of the underlying microscopic physics and to open the way to future device applications, it is desirable to integrate and to probe these materials in ultrafast electrical devices. Driven superconductivity is a case in point, as nonlinear transport (critical current) or magnetic field expulsion (Meissner effect) have not been reported to date. Here, we report ultrafast measurements of linear and nonlinear electrical transport in photo-excited thin films of K3C60, grown by Molecular Beam Epitaxy and patterned with a series of photo-conductive switches connected by high-frequency waveguides. Ultrafast linear and nonlinear transport measurements reveal the emergence of the same critical current response observed immediately below Tc = 20 K. The experiments reported here provide a unique signature of optically induced non-equilibrium superconductivity. |
Monday, March 6, 2023 9:12AM - 9:24AM |
A32.00007: Experimental study of strong light-matter interaction in graphene Hall bar devices Nikolai Kalugin, YIJING LIU, Gabriel Gaertner, John Huckabee, Alexey Suslov, Luis Foa Torres, Paola Barbara Strong light-matter interaction in graphene is predicted to induce Floquet-Bloch states which may also have non-trivial topology [1,2,3]. We report on the experimental observation of photoinduced transversal voltage and photoinduced current in graphene Hall bars irradiated with high-power linearly and circularly-polarized mid-Infrared radiation at cryogenic temperatures. The radiation wavelength is 10.6 microns and the power density is larger than 1 mW/micron^2. We measure the dependence of the photoresponse on the gate voltage, temperature, and light polarization. |
Monday, March 6, 2023 9:24AM - 9:36AM |
A32.00008: Chiral phonons with giant magnetic moment Swati Chaudhary, Gregory A Fiete Chiral phonons are phonons associated with the orbital motion of ions. These phonons carry finite angular momentum and exhibit many interesting magneto-phononic and phono-magnetic effects. On the basis of purely circular ionic motion, these phonons are expected to carry a magnetic moment of the order of a few nuclear magnetons. However, some recent experiments have demonstrated a phonon magnetic moment of the order of a few Bohr magnetons. This kind of giant magnetic response points towards the electronic contribution to the magnetic moment of phonons. Many diverse mechanisms have been discovered for this enhanced magnetic response of chiral phonons. The orbital-lattice coupling is one such mechanism where low-energy electronic excitations on a magnetic ion couple to phonons and impart a large magnetic moment to phonons. This mechanism has been extensively studied for rare-earth paramagnets where phonons couple to crystal electric field excitations on 4f electrons and exhibit a large phonon Zeeman effect. We propose that this mechanism can also manifest in d-electron systems where phonons can couple with spin-orbit excitations. After outlining the conditions required to observe this effect in transition-metal compounds, we present some group theoretical aspects and example systems that allow chiral phonons with a giant magnetic moment. We furthermore show that these systems should also exhibit very large phono-magnetic processes like the generation of effective magnetic fields by exciting chiral phonons. Such phonons can possibly be used for ultrafast control of quantum matter. |
Monday, March 6, 2023 9:36AM - 9:48AM |
A32.00009: Probing the Intralayer and Interlayer Dynamics of the Charge Density Wave Phases in 1T-TaS2 Nelson Hua, Simon Gerber, Corinna Burri, Dragan Mihailovic, Diling Zhu, Hasan Yavas, Takahiro Sato, Shih-Wen Huang, Yue CaO, Xun Jia, Vincent Esposito, Yanwen Sun, Matthias C Hoffmann, Ian K Robinson 1T-TaS2 is a van der Waals transition metal dichalcogenide (TMD) material with a rich phase diagram consisting of unique ‘Star of David’ charge density wave (CDW) states in thermal equilibrium, including the coexistence of superconducting and commensurate CDW states. Numerous studies have characterized the equilibrium phases through observables such as resistivity, optical reflectivity, and scanning tunneling microscopy, but experiments to study the nature of the recently discovered ‘hidden’ metastable CDW state have been less revealing. Of the myriad of TMDs, 1T-TaS2 is the only one that exhibits a low-temperature non-thermal switching from an insulating ground state to a gapless ‘hidden’ metallic state, not to mention its extremely large temporal range of tunable lifetimes. We performed an ultrafast X-ray diffraction experiment to access dynamic observables, the coherent oscillations from independent structural and electronic scattering peaks, to reveal directional and chiral dependencies that unveil the complexity of the domain structure that prior experiments failed to capture, particularly the nature of the interlayer and intralayer domain dynamics and their role in the commensurate CDW-hidden CDW nonequilibrium transition. |
Monday, March 6, 2023 9:48AM - 10:00AM |
A32.00010: Giant rectification in strongly-interacting boundary-driven tilted systems Juan J Mendoza-Arenas, Stephen R Clark Correlated quantum systems feature a wide range of nontrivial effects emerging from interactions between their constituting particles. In nonequilibrium scenarios, these manifest in phenomena such as many-body insulating states and anomalous scaling laws of currents of conserved quantities, key for applications in quantum circuit technologies. In this work [1] we propose a giant rectification scheme based on the asymmetric interplay between two ingredients that lead to insulating configurations on their own, namely strong particle interactions and a tilted potential. Based on exact and tensor network simulations, and on perturbative calculations, we show that while for reverse bias both terms cooperate and induce a strengthened insulator with exponentially suppressed current, for forward conduction they compete and generate current resonances; this results in rectification coefficients of many orders of magnitude. We uncover the mechanism underlying these resonances as enhanced coherences between energy eigenstates occurring at avoided crossings in the system's energy spectrum. Our proposal paves the way for implementing a perfect diode in currently-available quantum simulation platforms. |
Monday, March 6, 2023 10:00AM - 10:12AM |
A32.00011: Understanding the Effects of Dephasing on Bloch Wave Interferometry via Temperature Dependent Polarimetry of High-order Sidebands in GaAs Joseph Costello, Seamus O'Hara, Qile Wu, Loren N Pfeiffer, Ken West, Mark S Sherwin High-order sideband generation is a rich phenomenon in the field of strongly driven quantum matter based on interferometry of Bloch waves. Sidebands are created when electron-hole pairs in a semiconductor produced by a near infrared laser (NIR) are accelerated by an intense terahertz laser. Collision of these pairs leads to emission of sidebands at higher energies than the NIR. Since different Bloch waves can contribute to the creation of any sideband, the polarization of the sidebands is set by the interference of these waves. Previous work has used this polarization to reconstruct the Bloch wavefunctions of holes in GaAs [1]. |
Monday, March 6, 2023 10:12AM - 10:24AM |
A32.00012: Interference of Driven Quantum Wave Functions Measured through Stokes Polarimetry of High Order Sidebands Seamus O'Hara, Joseph Costello, Qile Wu, Kenneth W West, Loren N Pfeiffer, Mark S Sherwin Interferometry is often used to measure the difference in phase between two waves, including phases of quantum wave functions. Here we present measurements of the interference between the wave functions two hole species in Gallium Arsenide (GaAs) as they are driven from equilibrium by a large electromagnetic field and emit sideband photons. These photons are produced from a phenomenon called High-order Sideband Generation (HSG), where a near-infrared laser (NIR) creates electron-hole pairs in bulk GaAs and a large Terahertz (THz) field accelerates the pair to higher energy, until the pair eventually collide and emit a higher energy HSG photon [1]. The polarization of the HSG photon is set by the interference between the wave functions of the two hole states as a result of different dynamical phases accumulated during the THz acceleration process [2]. At increasing sideband energies, the e-h pairs cover longer paths in the Brillouin Zone (BZ) to gain more energy from the THz field. Using Stokes polarimetry, we measure both the change in linear orientation and ellipticity of the sidebands as a function of BZ path length, resulting in a novel interference pattern and providing insight into the dynamical processes of the non-equilibrium states in driven quantum matter. |
Monday, March 6, 2023 10:24AM - 10:36AM |
A32.00013: A theory proposal for extracting non-equilibrium dephasing rates from a terahertz Bloch wave interferometer in bulk GaAs Qile Wu, Mark S Sherwin Understanding dephasing mechanisms is important in the study of interactions between quasi-particles and manipulation of quantum coherences in solids. Of special interest are the dephasing mechanisms for driven systems far away from thermal equilibrium such as semiconductors in the condition of high-order sideband generation (HSG). HSG occur in a near-resonantly excited semiconductor that is driven by a sufficiently strong, terahertz (THz)-frequency electric field. Dephasing rates are key ingredients in determining the strengths and polarizations of the THz sidebands. For HSG in bulk GaAs, dynamical birefringence results from quantum interference of the spin-3/2 hole Bloch wave functions, such that ellipticity in the sidebands can arise from linearly polarized driven fields. The information about the hole quasi-particles, including their effective masses, pseudo-spins, and dephasing rates, is then coded in the sideband polarizations. We show that THz-driven materials such as bulk GaAs can be used as an interferometer of Bloch waves to extract dephasing rates of the electron-hole pairs in strong driving fields. Our work provides a way to explore non-equilibrium dephasing mechanisms in semiconductors and a principle for coherently controlling THz sideband emission. |
Monday, March 6, 2023 10:36AM - 10:48AM |
A32.00014: Dynamical quantum phase transition in mesoscopic superconducting system Kacper Wrzesniewski, Ireneusz Weymann, Nicholas Sedlmayr, Tadeusz Doma?ski We investigate the dynamics of correlated quantum dot sandwiched between the metallic and superconducting electrodes. In particular, we consider two quench protocols feasible experimentally. The first quench is performed in the coupling between the dot and the superconductor, while the other one abruptly shifts the energy of the orbital level. The time-dependent charge occupancy, on-dot pair correlations and transient currents reveal non-trivial interplay between the proximity induced electron pairing with correlations caused by the on-dot Coulomb repulsion. |
Monday, March 6, 2023 10:48AM - 11:00AM |
A32.00015: Nonlinear two-level time crystal dynamics Samuli Autti, Petri J Heikkinen, Jaakko Nissinen, Jere T Mäkinen, Grigori E Volovik, Vladislav V Zavjalov, Vladimir B Eltsov Time crystals are a novel phase of condensed matter, characterised by continuous, repeating motion in their quantum ground state. In our experiments, we explore this new phase using magnetic quasiparticles in the superfluid universe of 3He: We observe the formation of a quantum time quasicrystal and its transformation to a superfluid time crystal – a time supersolid [1]. We then bring two superfluid time crystals to touch each other, creating a time crystal two-level system. The two level system is characterised by AC Josephson/Rabi population oscilltions [2], a level crossing between the time crystals, and Landau-Zener population transfer between the levels [3]. These ground-breaking experiments substantiate the theoretical excursion started by Frank Wilczek, and provide a novel, magnetic building block for quantum devices and quantum information processing – potentially even at room temperature [4].
[1] S. Autti et al, PRL 120, 215301 (2018) [2] S. Autti et al, Nature Materials 20, 171–174 (2021) [3] S. Autti et al, Nature Comms. 13, 3829 (2022) [4] A. Kreil et al. Phys. Rev. B 104 144414 (2021) |
Monday, March 6, 2023 11:00AM - 11:12AM |
A32.00016: BROTOCs and Quantum Information Scrambling at Finite Temperature Namit Anand, Paolo Zanardi Out-of-time-ordered correlators (OTOCs) have been extensively studied in recent years as a diagnostic of quantum information scrambling. In this paper, we study quantum information-theoretic aspects of the regularized finite-temperature OTOC. We introduce analytical results for the bipartite regularized OTOC (BROTOC): the regularized OTOC averaged over random unitaries supported over a bipartition. We show that the BROTOC has several interesting properties, for example, it quantifies the purity of the associated thermofield double state and the operator purity of the analytically continued time-evolution operator. At infinite-temperature, it reduces to one minus the operator entanglement of the time-evolution operator. In the zero-temperature limit and for nondegenerate Hamiltonians, the BROTOC probes the groundstate entanglement. By computing long-time averages, we show that the equilibration value of the BROTOC is intimately related to eigenstate entanglement. Finally, we numerically study the equilibration value of the BROTOC for various physically relevant Hamiltonian models and comment on its ability to distinguish integrable and chaotic dynamics. |
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