Events
Astrophysics and Cosmology Seminar
Detecting individual stars at cosmological distances with gravitational lensing
Dr. Ashish Meena
BGU
Wed, 02 Apr 2025, 11:10
Sacta-Rashi Building for Physics (54), room 207
Abstract: Gravitational lensing refers to the bending of light rays coming from a distant source as they pass through the gravitational field of a mass distribution and has been a well established tool in astrophysics. One can show that, under certain conditions, gravitational lensing can lead to multiple image formations of the distant source and magnify these images. Recently, thanks to extreme lensing magnification boost, we have been able to detect and study individual stars halfway across the Universe. With the Hubble Space Telescope (HST) and JWST, the number of such objects has been continuously increasing. In my talk, I will discuss the basic idea behind how we search and detect these individual stars at cosmological distances and their applications. I will also talk about our recent detection of lensed star candidates in the MACS J0647.7+7015 galaxy cluster at a redshift of ≃4.8 when the Universe was only ~1.3 billion years old.
Quantum optics seminar
Atomic arrays as programmable quantum processors and sensors
Dr. Ran Finkelstein
Tel Aviv University
Wed, 02 Apr 2025, 16:00
Zoom Only
Abstract: Zoom link: https://us02web.zoom.us/j/85736135798?pwd=qGWvMTjKDbIVJr23lbzEm7BiIN7RtJ.1
Abstract:
Large arrays of trapped neutral atoms have emerged over the past few years as a promising platform for quantum information processing, combining inherent scalability with high-fidelity control and site-resolved readout. In this talk, I will discuss my recent work with arrays of Alkaline-earth atoms. These divalent atoms offer unique properties stemming largely from their long-lived metastable states, which form the basis of the optical atomic clock. I will describe the design of a universal quantum processor based on clock qubits and its application in quantum metrology.
First, we realize local control of individual clock qubits, which we utilize to extend the Ramsey interrogation time beyond the coherence time of a single atom. To realize a universal quantum processor, we further demonstrate record high-fidelity two-qubit entangling gates mediated by Rydberg interactions, which we combine with dynamical reconfiguration to entangle clock probes in a cascade of different GHZ states. Finally, we use the narrow clock transition to measure and remove thermal excitations of atoms in tweezers (a technique known as erasure conversion) which we utilize to generate hyperentangled states of motion and spin and to perform entanglement-assisted ancilla readout and parity checks. Time permits, I will also discuss another modality of analog quantum simulation with Rydberg atom arrays.
Condensed Matter Seminar
Shedding single-photon light on many-body physics
Mr. Amir Burshtein
TAU
Mon, 07 Apr 2025, 11:10
Sacta-Rashi Building for Physics (54), room 207
Abstract: Photon decay is a notoriously inefficient process. The culprit is the fine structure constant \alpha – while photon splitting into other photons at lower frequencies may be mediated by interaction with matter, the small value of \alpha (~1/137) famously sets this interaction in the perturbative regime. A qualitatively different picture can emerge in superconducting circuits: carefully designed waveguides, implemented by arrays of Josephson junctions, provide an order unity \alpha environment for the photons. Coupling the waveguide to artificial atoms (qubits) then leads to the simulation of strong light-matter interaction, allowing for the decay of a single photon with order unity probability, demonstrated in recent experiments. I will show how this exotic effect can be leveraged to illuminate surprising aspects of fundamental quantum many-body phenomena, observed in experiments from the Manucharyan (EPFL) and Kuzmin (UW-Madison) groups. I will explain how the scattering rates of the photons, natural observables in such experiments, can capture dynamical signatures of quantum tunneling events, reveal the existence of inelastic collisions in integrable systems, and explore the onset and the breakdown of Fermi’s golden rule. I will further show that the scattering of a single photon off an artificial atom can serve as a highly sensitive probe of a fragile quantum phase transition. These works set the stage for utilizing the strong light-matter interaction to study nonequilibrium setups and harnessing the efficient photon splitting for quantum information processing applications.
This talk is mostly based on the following papers (theory and experiment, respectively):
- AB and M. Goldstein, "Inelastic decay from Integrability", PRX Quantum 5 020323 (2024)
- R. Kuzmin, N. Mehta, N. Grabon, R. A. Mencia, AB, M. Goldstein, and V. E. Manucharyan, "Observation of the Schmid-Bulgadaev dissipative quantum phase transition", Nature Physics s41567-024-02695-7 (2024)
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