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 Physics at Virginia

"TBA"


Zekun Chu , University of Virginia
[Host: Cass Sackett]
ABSTRACT:

TBA

Atomic Physics Seminar
Monday, May 6, 2024
3:30 PM
, Room Dell 2 Building, Room 100
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"Phononic Frequency Combs"


Adarsh Ganesan , Ahmedabad University
[Host: Olivier Pfister]
ABSTRACT:

Phononic frequency combs (PFC) are the mechanical analogs of celebrated photonic frequency combs. These represent a newly documented physical phenomenon in the well researched physical domain of mechanical resonators [1]. The emergence of PFC is mediated by nonlinear modal coupling. Through a series of experiments using micromechanical resonators, various physical features of phononic frequency combs have been identified. These include drive parameters for comb operation, hysteresis for comb spectrum tailoring and nonlinear sensitivity to physical perturbations. My talk will describe the physics of phononic frequency combs and will emphasize how these combs could be foundational to the fields of materials science, molecular science and chemical science. In that respect, I will present our first conceptual demonstrations of material combs, molecular combs and chemical combs respectively. I will also showcase our recent demonstration of broadband phononic combs using optical tweezers [2]. The future work will be focused on the applications of phononic frequency combs in sensing, communications and quantum information science.

 

1. Ganesan, A., Do, C. and Seshia, A., 2017. Phononic frequency comb via intrinsic three-wave mixing. Physical review letters, 118(3), p.033903.

2. de Jong, M.H., Ganesan, A., Cupertino, A., Gröblacher, S. and Norte, R.A., 2023. Mechanical overtone frequency combs. Nature Communications, 14(1), p.1458.

Atomic Physics Seminar
Monday, September 25, 2023
3:30 PM
Clark Hall, Room G004
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https://virginia.zoom.us/j/93772850932?pwd=ZUVWYXdpMjFybDZpY3RIWURzSUJKQT09

 

Meeting ID: 937 7285 0932

Passcode: 507316


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"Rydberg atoms arrays for applications with QuEra 256-qubit machine"


Tommaso Macri , Harvard University
[Host: Peter Schauss]
ABSTRACT:

Rydberg atom arrays have emerged in the past few years as a promising resource for quantum technologies. The ability to produce arbitrary spatial arrangements of neutral atoms is combined with the coherent control of their internal states, including coupling to Rydberg states to achieve strong interactions, to create an extremely versatile platform. Recent experiments on arbitrary two-dimensional arrays have highlighted the potential of this system for high-fidelity quantum simulation of exotic phases of matter and for optimization problems. I will present prototypical examples of theoretical and experimental efforts to tackle such problems with Aquila, QuEra 256-qubit machine.

Atomic Physics Seminar
Monday, April 17, 2023
4:00 PM
Warner, Room 110
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ABSTRACT:

Macroscopic quantum phenomena, such as observed in superfluids and superconductors, have led to promising technological advancements and some of the most important tests of fundamental physics. At present, quantum detection of light is mostly relegated to the microscale, where avalanche photodiodes are very sensitive to distinguishing single-photon events from vacuum but cannot differentiate between larger photon-number events. Beyond this, the ability to perform measurements to resolve photon numbers is highly desirable for a variety of quantum information applications, including computation, sensing and cryptography. True photon-number resolving detectors do exist, but they are currently limited to the ability to resolve on the order of 10 photons, which is too small for several quantum-state generation methods based on heralded detection. In this talk I’ll explain how we extended photon measurement into the mesoscopic regime by implementing a detection scheme based on multiplexing highly quantum-efficient transition-edge sensors to accurately resolve photon numbers between 0 and 100. Then I’ll demonstrate the use of our system by explaining how we implemented a quantum random-number generator with no inherent bias. This method is based on sampling a coherent state in the photon-number basis and is robust against environmental noise, phase and amplitude fluctuations in the laser, loss and detector inefficiency as well as eavesdropping. Beyond true random-number generation, our detection scheme serves as a means to implement quantum measurement and engineering techniques valuable for photonic quantum information processing.

Atomic Physics Seminar
Monday, March 27, 2023
4:00 PM
Warner, Room 110
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"Quantum computing with neutral ytterbium atoms"


Jeff Thompson , Princeton University
[Host: Peter Schauss]
ABSTRACT:

Quantum computing with neutral atoms has progressed rapidly in recent years, combining large system sizes, flexible and dynamic connectivity, and quickly improving gate fidelities. The pioneering work in this field has been implemented using alkali atoms, primarily rubidium and cesium. However, divalent, alkaline-earth-like atoms such as ytterbium offer significant technical advantages. In this talk, I will present our progress on quantum computing using 171-Yb atoms, including high-fidelity imaging, nuclear spin qubits with extremely long coherence times, and two-qubit gates on nuclear spins using Rydberg states [1,2]. I will also discuss several unexpected benefits of alkaline-earth-atoms: an extremely robust and power-efficient local gate addressing scheme [3], and a novel approach to quantum error correction called “erasure conversion”, which has the potential to implement the surface code with a threshold exceeding 4%, using the unique level structure of 171-Yb to convert spontaneous emission events into erasure errors [4].

 

[1] S. Saskin et al, Phys. Rev. Lett. 122, 143002 (2019).
[2] A. P. Burgers et al, PRX Quantum 3, 020326 (2022).
[3] S. Ma, A. P. Burgers, et al, Phys. Rev. X 12, 021028 (2022).
[4] Y. Wu, et al, Nat. Comms. 13, 4657 (2022).

Atomic Physics Seminar
Tuesday, February 28, 2023
3:30 PM
Gilmer Hall, Room 257
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Note special room.

Join Zoom Meeting

https://virginia.zoom.us/j/91951026141?pwd=ZUw0eHJzS2tDa0VrS3FlM0IrYVVCdz09

 

Meeting ID: 919 5102 6141

Passcode: 043741


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"Building and Characterizing an Atom Interferometer Gyroscope"


Marybeth Beydler
[Host: Prof. Peter Schauss]
ABSTRACT:

Inertial Navigation Systems (INS) are alternatives to GPS that operate using linear accelerometers and gyroscopes to calculate the user’s position, orientation, and velocity using no external reference. Optical Sagnac gyroscopes are part of modern day INS and are limited by their ability to measure small rotations as they need a very large enclosed area. The Bragg Interferometer Gyroscope in a Time Orbiting Potential Trap (BIGTOP) is a rotation detector using a Bose-Einstein Condensate (BEC) to execute two Sagnac interferometers in a magnetic trap. BIGTOP is an improvement upon a previous iteration of a dual Sagnac interferometer which demonstrated rotation sensing. We have achieved atom interferometry with BIGTOP and reached a Sagnac area of 8 mm2 using multiple orbits, an improvement by a factor of 16. Additionally, we have taken our first large dataset over the course of 24 hours, which can be used to analyze the stability of our system. In tandem with BIGTOP, we have also worked to characterize and operate a compact atom chip interferometer system built by Cold Quanta (CQsystem). We report BIGTOP results, progress with the CQ system, and future work.

Atomic Physics Seminar
Monday, November 21, 2022
4:00 PM
Chemistry Building , Room 206
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"Moving Beyond Scalar Quantum Sensing with Cold-Atom Interferometers"


Brynle Barrett , University of New Brunswick
[Host: Cass Sackett]
ABSTRACT:

Robust and accurate acceleration tracking remains a challenge in many fields. For geophysics and economic geology, precise gravity mapping requires onboard sensors combined with accurate positioning and navigation systems. Cold-atom-based quantum inertial sensors can provide such high-precision instruments. However, current scalar instruments require precise alignment with vector quantities such as gravity. This presents a significant challenge in mobile environments. In recent work, we realized the first “vectorial” quantum accelerometer by combining three orthogonal atom interferometer measurements with a classical accelerometer triad. We demonstrate acceleration vector tracking with a 50-fold improvement in stability compared to our navigation-grade classical accelerometers. In this talk, I will give an overview of our vectorial quantum sensor and discuss future work moving beyond scalar quantum sensing.

Atomic Physics Seminar
Monday, November 7, 2022
4:00 PM
Chemistry Building, Room 206
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Note special room.

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