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CQRT Seminars

The Atomic, Molecular and Optical (AMO) and Condensed Matter (CM) physics groups are hosting a joint seminar as part of the Center for Quantum Research and Technology (CQRT).  This endowed seminar series brings in experts from across the country as well as across campus to discuss the latest in research advances in quantum science.

Seminars in Fall 2021 will be conducted over Zoom and will be held on Tuesdays from 1:15-2:15pm or Fridays from 12:15-1:15pm, depending upon speaker availability.  If you wish to attend a seminar and are not on our mailing list, please contact either Kieran Mullen (kieran@ou.edu)  or Robert Lewis-Swan  (lewisswan@ou.edu) to obtain a link.

Fall 2021 (virtual Zoom series)

Title: High-precision physics and chemistry with ultracold molecules

Tanya Zelevinsky, Columbia University

Tuesday, August 24, 2021
1:15-2:15pm (Zoom link will be announced)

Abstract:  Techniques for controlling the internal quantum states and motion of atoms have led to extremely precise metrology and studies of degenerate gases.  Extending such techniques to various types of molecules further enriches the understanding of fundamental physics, basic chemical processes, and many-body science.  Samples of diatomic molecules can be created by binding laser-cooled atoms, or by direct molecular laser cooling.  We explore both approaches and demonstrate high-precision metrology with an optical-lattice based molecular clock as well as chemistry in the highly nonclassical domain.

Title: Topological physics: from photons to electrons

Mohammad Hafezi, University of Maryland

Friday, September 3, 2021
12:15-1:15pm (Zoom link will be announced)

Abstract:  here are many intriguing physical phenomena that are associated with topological features --- global properties that are not discernible locally. The best-known examples are quantum Hall effects in electronic systems, where insensitivity to local properties manifests itself as conductance through edge states which are insensitive to defects and disorder. In the talk, we first discuss how similar physics can be explored with photons; specifically, how various topological models can be simulated in various photonics systems, from ring resonators to photonic crystals. We then discuss that the integration of strong optical nonlinearity can lead to unique bosonic phenomena, such as topological frequency combs, topological source of quantum light, and chiral quantum optics. These results may enable the development of classical and quantum optical devices with built-in protection for next-generation optoelectronic and quantum technologies. In the end, we discuss an emerging field at the interface of quantum optics and correlated electron systems, with the goal of creating and manipulating many-body states of light-matter hybrids with new functionalities, such as high-Tc superconductors.  

Title:   Synthetic dimensions in ultracold quantum matter

Kaden Hazzard, Rice University

Tuesday, September 7, 2021
1:15-2:15pm (Zoom link will be announced)

Abstract:  A synthetic dimension is a degree of freedom where motion in space is mimicked by motion through other states, such as hyperfine states of atoms or rotations of molecules. These states act as lattice sites in extra spatial dimensions, and can be used alone or in combination with any real spatial dimensions. The superb control of internal degrees of freedom opens a vast new frontier in quantum science, both for simulating phenomena in condensed matter (such as topological band structures or fracton matter) and for studying phenomena that don't occur elsewhere in nature, such as fluctuating quantum strings, embranes, and even 3-branes that fluctuate in 4D. 

In this talk I will discuss our theoretical understanding of synthetic dimensions, and the rapid experimental progress exploring synthetic dimensions made with three types of ultracold matter: Rydberg atoms, molecules, and momentum-space lattices. 

Title:  Simulating many-body physics using quantum tensor networks

Michael Foss-Feig, Honeywell

Friday, September 17, 2021
12:15-1:15pm (Zoom link will be announced)

Abstract:  Tensor network techniques exploit the structure of entanglement to dramatically reduce the difficulty of simulating quantum systems on classical computers. But these techniques have limitations, and many problems in many-body quantum physics, for example simulating dynamics, remain intractable despite decades of effort to solve them.  Quantum computers offer an alternative route to simulating quantum systems that is in principle efficient, but their small size and limited fidelities have so far prevented solution of problems of real practical interest that cannot be solved classically.  Here we discuss prospects for combining these two techniques by directly representing tensor-network states as quantum circuits, and show that recent developments in quantum hardware make it possible to carry out quantitatively accurate simulations of quantum dynamics directly in the thermodynamic (infinite system size) limit using a small number of qubits.

Title: Entangled Bose-Einstein condensates in momentum space

Carsten Klempt, Leibniz University Hannover

Tuesday, September 21, 2021
1:15-2:15pm (Zoom link will be announced)

Abstract:  The generation and application of entangled many-particle states is a central goal of the second quantum revolution. In our work, we employ spin-changing collisions to create spin entanglement in atomic Bose-Einstein condensates. I will present our work towards transferring this entanglement towards external degrees of freedom. The successful transfer of spin entanglement to momentum states presents an important step towards the operation of future atom interferometers with a sensitivity beyond the Standard Quantum Limit.

Title: Dipolar Quantum Gases of Magnetic Lanthanide Atoms: achievements and future opportunities

Francesca Ferlaino, University of Innsbruck

Tuesday, September 28, 2021
1:15-2:15pm (Zoom link will be announced)

Abstract:   Since its creation, the field of ultracold atoms has been through fantastic developments. Some of the most recent include the development of quantum-gas microscopes, atom tweezers, and various forms of interaction engineering. Each of these experimental advances has allowed new quantum phenomena to be accessed and observed. A further important development is based on the use of more exotic atomic species, whose peculiar atomic properties have allowed to broaden the horizons of investigation.

This talk aims to retrace the new opportunities that have emerged from the use of quantum gases composed of the strongly magnetic erbium and dysprosium atoms from the perspective of the Innsbruck experiments.
Thanks to their large magnetic moment, these species exhibit a large dipolar interaction that has allowed us to observe rotonic excitations, quantum droplets, and supersolid states. Moreover, their dense atomic spectrum has also made possible to implement new optical manipulation schemes, and more recently the observation of an Hz-wide transition in the telecom frequency region promises new possibilities in quantum optics.

Title: Observation of a Transition between Dynamical Phases in a Quantum Degenerate Fermi Gas

Joseph Thywissen, University of Toronto

Tuesday, October 5, 2021
1:15-2:15pm (Zoom link will be announced)

Abstract:   I will discuss collective dynamics of ultracold fermions, in two contexts. First, I will discuss a study of spin dynamics near the non-interacting point of an s-wave Feshbach resonance. The collective enhancement of weak interactions allows for an interesting range of behaviors, including a non-equilibrium phase transition. Second, I will discuss a proposal to study collective orbital dynamics of spin-polarized fermions in an optical lattice.

A proposed paradigm for out-of-equilibrium quantum systems is that an analogue of quantum phase transitions exists between parameter regimes of qualitatively distinct time-dependent behavior. We present evidence of such a transition between dynamical phases in a cold-atom quantum simulator of the collective Heisenberg model. Our simulator encodes spin in the hyperfine states of ultracold fermionic potassium. Atoms are pinned in a network of single-particle modes, whose spatial extent emulates the long-range interactions of traditional quantum magnets. We find that, below a critical interaction strength, magnetization of an initially polarized fermionic gas decays quickly, while above the transition point, the magnetization becomes long-lived, due to an energy gap that protects against dephasing by the inhomogeneous axial field. Our quantum simulation reveals a non-equilibrium transition predicted to exist but not yet directly observed in quenched s-wave superconductors. 

In the second part of the talk, I discuss non-equilibrium orbital dynamics of spin-polarized ultracold fermions in the first excited band of an optical lattice. A specific lattice depth and filling configuration is designed to allow the px and py excited orbital degrees of freedom to act as a pseudo-spin. Bragg dressing can reduce single-particle dispersion rates, such that a collective many-body gap is opened with only moderate Feshbach enhancement of p-wave interactions. Time permitting, I will discuss the first experimental steps towards realizing this proposal. 

Title: A quick visit to the world of quantum graphs

Alejandro Chávez-Domínguez, OU Mathematics

Friday, October 15, 2021

12:15-1:15pm (Zoom link will be announced)

Abstract:  A classical graph consists of a set of vertices, some pairs of which are joined by edges. In contrast, a quantum graph is a linear space of square matrices with complex entries, containing the identity matrix and closed under taking the conjugate transpose. This seemingly strange notion has its origins in Quantum Information Theory, where such objects play a role that in  classical Information Theory is occupied by a classical graph.

In the talk I will explain the analogy relating classical and quantum graphs, and will present a couple of examples of recently-developed quantum versions of some geometric notions from classical graph theory. Based on joint works with Andrew Swift.

Title: Site-specific spectroscopic measurement of spin and charge in (LuFeO3)m/(LuFe2O4)1 multiferroic superlattices

Janice Musfeldt, University of Tennessee

Tuesday, October 26, 2021
1:15-2:15pm (Zoom link will be announced)

Abstract:  TBA

Title: TBA

Todd Pittman,  UMBC

Tuesday, November 2, 2021
1:15-2:15pm (Zoom link will be announced)

Abstract:  TBA

Title: The Quantum Neutron

Charles Clark, NIST, JQI and Univ. of Maryland

Date: Friday, November 5, 2021
12:15-1:15pm LH 105 and on Zoom  (Zoom link will be announced)

Abstract:   I present a simple overview of the particle and wave properties of the neutron, with emphasis on their parallels in light, electrons and atoms. Neutron interferometry enables one to realize the quantum limit of the Young double slit experiment, when no mor that only neutron is ever present in the interferometer. How can only one neutron go through both slits? We have used neutron interferometry and holography to address some of the questions of structured waves of light and matter that have been studied with photons, electrons and atoms.​

 

Title: TBA

Alejandro Manjavacas,  Instituto de Óptica ( CSIC)/University of New Mexico.

Tuesday, November 9, 2021
1:15-2:15pm (Zoom link will be announced)

Abstract:  TBA

Title: TBA

 Zhe-Xuan Gong, Colorado School of Mines

Tuesday, November 16, 2021
1:15-2:15pm (Zoom link will be announced)

Abstract:   TBA

Title: TBA

Hillary Hurst, San Jose State University

Friday, November 19, 2021
12:15-1:15pm (Zoom link will be announced)

Abstract:  TBA

Title: TBA

Maria Kamanetska, Boston University

Tuesday, November 30, 2021
1:15-2:15pm (Zoom link will be announced)

Abstract:  TBA

Spring 2021 (virtual Zoom series)

Title: Advanced laser development for uses in fundamental research into the Standard Model, quantum computation, and to the highest powers in industry

Dawn Meekhof, Lockheed Martin Laser and Sensor Systems

Friday, February 12, 2021
12:15-1:15pm (Zoom link will be announced)

Abstract: Laser technology grew out of advanced pure research, and has proven to be an excellent new tool for many fields. My career has required developing new lasers for fundamental research into the Standard Model, for quantum computation, atomic clocks, advanced telecom products, medical devices, and defense systems. For some of this work, reaching an exact wavelength with 1 mW was necessary, for others building a massive system with 100kW. My career path has taken the laser technology from working to answer the most fundamental of scientific questions to practical applications in industry. In this talk, I will discuss the laser technology, the research, the applications, and how a scientific career in our world can evolve. 

Title: Room temperature polaritonics in all-inorganic cesium lead halide perovskite

Carole Diederichs, Physics Laboratory of the Ecole Normale Supérieure (LPENS), Sorbonne University.

Tuesday, February 16, 2021
1:15-2:15pm (Zoom link will be announced)

Abstract: Strong light-matter coupling in microcavities of various dimensionalities and the resulting hybrid exciton-photon quasiparticles, i.e. the exciton-polaritons, have been reported in a wide range of organic and inorganic semiconductors. While demonstrations of the polariton Bose-Einstein condensation, which is at the heart of promising applications such as polariton lasers, all-optical polaritonic circuits or polariton quantum simulators, are limited within a handful of semiconductors at both low and room temperatures. In inorganic materials, polariton condensation significantly relies on sophisticated epitaxial growth, while organic active media usually suffer from large threshold density and weaker nonlinearities. In this respect, strong efforts have been done in hybrid organic-inorganic perovskite materials, as they combine the advantages of both inorganic and organic materials. However, up to now, polariton condensation has not been observed in such materials. The all-inorganic cesium lead halide perovskites are now part of a class of materials that are drawing attention for polaritonics at room temperature. The epitaxy-free fabrication combined with their excellent optical gain properties, their tunable emission from UV to NIR, and their better optical stability under high laser flux illumination compared with hybrid perovskites, promise further important technological developments. In this seminar, I will present our first results on polariton condensation at room temperature in all-inorganic perovskite microplatelets embedded in planar microcavities, which opened the way to the demonstration of polariton condensates propagation in perovskite microwires and polariton condensation in perovskite lattices that will be also presented. These realizations in epitaxy-free wavelength-tunable materials advocates the great promise of perovskite for polaritonics applications.

Title: Chip-scale electrically-pumped optical frequency combs

Lukasz Sterczewski, JPL

Tuesday, February 23, 2021
1:15-2:15pm (Zoom link will be announced)

Abstract: Chip-scale optical frequency combs (OFC) merge the concept of spectrally broadband emission with coherent laser radiation in a compact footprint. Hundreds to thousands equidistant phase-locked lines synchronized by intracavity nonlinearities have found many applications ranging from telecommunication to optical sensing. To date, however, most developments have been made in the near-IR region at telecom wavelengths. The mid-IR region above 3 µm of wavelength is particularly attractive for optical sensing of hydrocarbons associated with the existence of life. Unfortunately, mid-IR wavelengths still pose a technological challenge and limit the number of available OFC platforms.

One of the efficient ways to generate mid-IR OFCs is to exploit inherent nonlinearities in semiconductor lasers. In this seminar, we will discuss recent progress in interband cascade laser (ICL) OFCs. These sources analogous to that used in the tunable laser spectrometer (TLS) have shown excellent OFC properties with great suitability for free-running dual-comb spectroscopy. The same ICL material has also been used for fabricating GHz-bandwidths room-temperature photodetectors to demonstrate a self-contained room-temperature dual-comb spectrometer. The seminar will also briefly cover mid-IR diode laser OFCs, which have recently extended the portfolio of electrically-pumped OFCs.

Bio: Dr. Lukasz Sterczewski has been a NASA Postdoctoral Program (NPP) research fellow in the Microdevices Laboratory at JPL (389R) since 2019. At MDL, he was responsible for device testing and characterization to optimize the spectral properties of interband cascade laser frequency combs. His doctoral work conducted in the PULSE laboratory at Princeton University, and THz laboratory at Wroclaw University of Science and Technology, Poland, focused on frequency comb spectroscopy in the presence of excessive amounts of noise and unstabilized operation of semiconductor laser sources.

Title:  Atom-based storage and manipulation of electromagnetic signals: a cold-atom quantum memory and a room-temperature atomic radio

Lindsay LeBlanc, University of Alberta.

Friday, March 5, 2021 
12:15-1:15pm (Zoom link will be announced)

Abstract: The ability to store and manipulate quantum information encoded in electromagnetic (often optical) signals represents one of the key tasks for quantum communications and computation schemes. In this talk, I will discuss two platforms our group is using to manipulate electromagnetic signals with atoms:  With a cold-atom system, we have developed and characterized an efficient and broadband quantum memory that operates in a regime that makes use of Autler-Townes splitting (ATS). We demonstrate on-demand storage and retrieval of both high-power and less-than-one-photon optical signals with total efficiencies up to 30%, using the ground state spin-wave as our storage states. We also realize a number of photonic manipulations, including temporal beamsplitting, frequency conversion, and pulse shaping.  In a second, a room-temperature atomic vapour system, we have developed a scheme for radio signal transduction between a microwave and an optical carrier, all mediated through the atoms with the help of a resonant microwave cavity.  We are further exploring this promising atomic-vapour + microwave-cavity platform for applications related to optical quantum memory and quantum sensing.

Title: Commercialising Silicon Quantum Computers

James Palles-Dimmock, Quantum Motion

Friday, March 12, 2021

12.15-1.15pm (Zoom link will be provided)

Abstract: Given that the highest impact applications of quantum computers will need a million plus qubits, how can we get there as quickly as possible? In this talk I will summarise the key hurdles that need to be overcome in order to realise a scalable quantum processor and describe Quantum Motion’s approach. Quantum Motion is developing a quantum processor based on gate defined quantum dot spin qubits in silicon, I will contrast this with other approaches and highlight the particular benefits of our approach and some of our most recent published results.

Title: Predicting the properties of Ga2O3 using first-principles calculations

Hartwin Peelaers, University of Kansas

Tuesday, March 23, 2021
1:15-2:15pm (Zoom link will be announced)

Abstract: Gallium oxide (β-Ga2O3) is a promising material for high-power electronic devices, as it combines excellent material properties with ease of mass production. It is a wide-band-gap semiconductor (band gap of 4.8 eV) with a monoclinic crystal structure. Its high carrier mobility and large band gap have attracted a lot of attention for use in high-power electronics and transparent conducting applications. 

These applications require the presence of large concentrations of free carriers. Based on first-principles calculations using hybrid functionals, I will discuss different approaches to efficiently create free carriers in Ga2O3. Their presence can lead to additional light absorption, both through direct absorption, but also through phonon- or defect-mediated indirect absorption. Both types of absorption give rise to distinct absorption features, which have been observed recently. Finally, I will discuss how calculations can give insights in various methods to tailor the properties of Ga2O3.

Title: TBD
Qiang Lin, Electrical and Computer Engineering, University of Rochester

Tuesday, March 30, 2021
1:15pm-2:15pm (Zoom link will be announced)

 

Title: Single-, few-, and many-photon physics in mesoscopic atomic chains
Ana Asenjo-Garcia, Columbia University 

Friday, April 9, 2021
12:15pm-1:15pm (Zoom link will be announced)

Abstract: Tightly packed ordered arrays of atoms (or, more generally, quantum emitters) exhibit remarkable collective optical properties, as dissipation in the form of photon emission is correlated. In this talk, I will discuss the single-, few- and many-body out-of-equilibrium physics of 1D arrays, and their potential to realize versatile light-matter interfaces. For small enough inter-atomic distances, atomic chains feature dark states that allow for dissipationless transport of photons, behaving as waveguides for single-photon states. Atomic waveguides can be used to mediate interactions between impurity qubits coupled to the array, and allow for the realization of multiple paradigms in waveguide QED, from bandgap physics to chiral quantum optics. Due to the two-level nature of the atoms, atomic waveguides are a perfect playground to realize strong photon-photon interactions. At the many-body level, I will address the open question of how the geometry of the array impacts the process of “Dicke superradiance”, where fully inverted atoms synchronize as they de-excite, emitting light in a burst (in contrast to the exponential decay expected from independent emitters). While most literature attributes the quenching of superradiance to Hamiltonian dipole-dipole interactions, the actual culprits are dissipative processes in the form of photon emission into different optical modes. I will provide an understanding of the physics in terms of collective jump operators and demonstrate that superradiance survives at small inter-atomic distances. I will finish my talk by discussing the implications of correlated photon emission for quantum information processing and metrology.

Title:  Colloidal Semiconductor Nanocrystals: (Un)Conventional and Quantum Materials and Devices

Cherie R. Kagan, University of Pennsylvania, Departments of Electrical and Systems Engineering, Materials Science and Engineering, and Chemistry

Tuesday, April 13,  2021
1:15-2:15pm (Zoom link will be announced)

Abstract: Colloidal semiconductor nanocrystals (NCs) are typically 2-20 nm diameter fragments of the bulk solid. They are known as “artificial atoms” since electrons, holes, and excitons are quantum-mechanically confined and occupy discrete electronic states. Advances in wet-chemical synthetic methods enable the preparation of NCs tailorable in size, shape, composition, and surface chemistry. As colloids, these NCs are readily dispersed in solvents and deposited using solution-based methods. They can self-assemble to form glassy or crystalline NC solids or be directed to assemble to deterministically position single or countable numbers of NCs. I will focus on routes to design solid-state NC materials by manipulating the NC surface chemistry to strengthen electronic coupling, by exchanging the ligands used in synthesis for more compact chemistries, and NC doping, by introducing atoms and ions that serve as impurities or modify stoichiometry. Ultimately, I will connect NC material design to their physical properties and their application in (un)conventional electronic and optoelectronic devices. I will also give an outlook on the opportunity to exploit NCs as platforms for quantum information science, in particular as optically addressable qubits.

Title: Imaging and time-stamping optical photons with nanosecond resolution for QIS applications

Andrei Nomerotski, BNL

Friday, April 16, 2021
12:15-1:15pm (Zoom link will be announced)

Abstract: I will discuss fast optical cameras based on the back-illuminated silicon sensor and Timepix3 ASIC. The sensor has high quantum efficiency and the chip provides ns scale resolution and data-driven readout with 80Mpix/sec bandwidth. The intensified version of the camera is single photon sensitive and since recently has been used for registration of entangled photons in long-distance quantum networks and for a variety of quantum imaging experiments as well as for other applications such as imaging mass spectroscopy, time-resolved neutron detection and lifetime imaging. I will show recent results focusing on the quantum applications and will discuss possible future directions for the technology.

Title: Non-equilibrium phenomena of ultracold quantum gasses trapped in optical lattice potentials

Charles Brown, UC Berkeley

Tuesday, April 20, 2021
1:15-2:15pm (Zoom link will be announced)

Abstract: Experiments with quantum gasses trapped in optical lattices, an analog of particles in a solid crystalline lattice, shed light on the behavior of condensed-matter systems, including solid-state materials.  Studying non-equilibrium phenomena of quantum gasses in optical lattices provides a method to explore how a lattice’s energy band structure is augmented by inter-particle interactions (band renormalization). Separately, studying such phenomena provides a method to explore the geometric and topological structure of a lattice’s energy bands. These studies are aided by experimental probes that are unavailable to solid-state systems.

In the first part of my talk, I will describe our recent work towards understanding the effects of frustration in a system of bosonic atoms trapped in a unique lattice made of light – an optical kagome lattice. Here, we create a Bose-Einstein condensate, accelerate it, then trap it in the lattice. In doing so, we probe a special energy band of the lattice, which is expected to be dispersionless (flat, as a function of quasimomentum). However, our measurements show that interactions between atoms reintroduce band curvature by deforming the lattice away from the kagome geometry. In the second part of my talk, I will describe our current effort to understand the geometric and topological properties of energy bands, by using a new technique to explore singularities at touching points between two bands.

Title: A quick visit to the world of quantum graphs CANCELED!!!!

Alejandro Chávez-Domínguez, OU

Friday, April 30, 2021

12:15-1:15pm (Zoom link will be announced)

Abstract: A classical graph consists of a set of vertices, some pairs of which are joined by edges. In contrast, a quantum graph is a linear space of square matrices with complex entries, containing the identity matrix and closed under taking the conjugate transpose. This seemingly strange notion has its origins in Quantum Information Theory, where such objects play a role that in  classical Information Theory is occupied by a classical graph.

In the talk I will explain the analogy relating classical and quantum graphs, and will present a couple of examples of recently-developed quantum versions of some geometric notions from classical graph theory. Based on joint works with Andrew Swift.

THIS EVENT IS HOSTED BY CQRT STUDENTS

Title: Catching the wave: preparing for the "quantum decade"

Travis Scholten, IBM Quantum

Tuesday, May 4, 2021

1:15-2:15pm (Zoom link will be announced)

Abstract: Over the past 5 years, quantum computing has migrated out of the lab, and into the world. Over the next 10 years, it is anticipated that advances in this technology will enable quantum computers to become part of enterprise-scale computing workloads. I discuss some near-term applications of quantum computers, connect them to business-relevant problems, and explore how proposed roadmaps for scaling quantum technology necessitate collaborations of people from a wide variety of backgrounds, including those in quantum networking. Finally, I share perspective on my own journey to the industry, lessons learned, and what most excites me about the coming quantum decade.