NYU Arts & Science

All Scheduled Events

July 18, 2024 Thursday 11:00 AM  +
726 Broadway, Room 1067
Center for Quantum Information Physics Seminars (cqip)


Axel LeBlanc
CEA Grenoble Center

Current phase relation engineering in Ge-based JoFETs

Recently, parity-protected superconducting qubits have emerged as promising candidates for enhancing the lifetime of quantum states. This innovative approach leverages sin(2φ) Josephson elements dominated by charge-4e supercurrent, which is the coherent transfer of pairs of Cooper pairs. In this study, we examine a highly transparent S-Sm-S Josephson field effect transistor (JoFET) fabricated from SiGe/Ge heterostructures. Initially, we utilize a SQUID with a wide and narrow JoFET to demonstrate that the current-phase relation comprises multiple and gate-tunable harmonics corresponding to charge-2ne (with n an integer) supercurrent. Their contribution is confirmed by DC measurements under radio-frequency irradiation that exhibit integer and half-integer Shapiro steps. Second, by harnessing the superconducting diode effect in a SQUID with two similar JoFETs, we identify the regime of perfect critical current symmetry. In this configuration, Shapiro steps measurements at half flux quantum reveal a pronounced reduction in the first harmonic thereby realizing a sin(2φ) Josephson element. Third, in a double SQUID device, we conduct a direct measurement of the CPR of a symmetric SQUID and report its harmonic content gate and flux-tunability. In a finely tuned configuration, we achieve a regime where the sin(2φ) component accounts for more than 95% of the total supercurrent. This result demonstrates a new promising route for the realization of parity-protected superconducting qubits with enhanced coherence properties.


July 25, 2024 Thursday 11:00 AM  +
726 Broadway, Room 1067
Center for Quantum Information Physics Seminars (cqip)


Vedangi Pathak
University of British Columbia

Spontaneous time-reversal breaking in d-wave superconducting heterostructures

In this seminar, I will present recent advancements in the study of time-reversal symmetry breaking phases in superconducting heterostructures of high-Tc cuprate superconductors. I will focus on two distinct superconducting heterostructures that exhibit d+id′ and d+is order parameters, respectively. Bilayers made of high-Tc cuprate superconductor (Bi2Sr2CaCu2O8) assembled with a twist angle close to have been recently shown to spontaneously break time reversal symmetry , consistent with theoretical predictions for emergent chiral topological phase in such twisted -wave superconductors. I will explore methods for estimating the magnitude of spontaneous chiral edge currents in the time-reversal symmetry-broken phase using a minimal microscopic model. Additionally, I will show that the magnetic fields generated by these edge currents, while small, are above the detection threshold of the state-of-the-art magnetic scanning probe microscopy. Next, I will discuss time- reversal symmetry breaking in the heterostructure of a high-Tc cuprate and a conventional s-wave superconductor, resulting in a non-topological d+is superconductor. I will share insights from our ongoing research on frustrated edge currents and spontaneous flux patterns at the edges of such superconductors. Finally, I will explore how the time-reversal symmetry breaking in these systems can be harnessed for the development of novel superconducting qubits and other device applications.


September 3, 2024 Tuesday 2:00 PM  +
726 Broadway, 1067, CQP Seminar
Center for Quantum Phenomena Seminars (cqp)


Zhang Carolyn Chuchu
Harvard University

TBA



September 10, 2024 Tuesday 2:00 PM  +
726 Broadway, 1067, CQP Seminar
Center for Quantum Phenomena Seminars (cqp)


Jeremy Johnson
Brigham Young University

TBA



September 17, 2024 Tuesday 2:00 PM  +
726 Broadway, 1067, CQP Seminar
Center for Quantum Phenomena Seminars (cqp)


Apoorv Tiwari
University of Copenhagen

TBA



September 26, 2024 Thursday 11:00 AM  +
726 Broadway, Room 1067
Center for Quantum Information Physics Seminars (cqip)


Wolfgang Pfaff
University of Illinois at Urbana-Champaign

TBA



September 30, 2024 Monday 10:00 AM  +
726 Broadway, Room 1067
Center for Quantum Information Physics Seminars (cqip)


Eli Levenson-Falk
University of Southern California

TBA



October 8, 2024 Tuesday 2:00 PM  +
726 Broadway, 1067, CQP Seminar
Center for Quantum Phenomena Seminars (cqp)


Aharon Kapitulnik
Stanford University

TBA



October 15, 2024 Tuesday 2:00 PM  +
726 Broadway, 1067, CQP Seminar
Center for Quantum Phenomena Seminars (cqp)


Kenneth Burch
Boston College

TBA



October 17, 2024 Thursday 11:00 AM  +
726 Broadway, Room 1067
Center for Quantum Information Physics Seminars (cqip)


David Perconte
Institut Neel Grenoble

TBA



October 22, 2024 Tuesday 2:00 PM  +
726 Broadway, 1067, CQP Seminar
Center for Quantum Phenomena Seminars (cqp)


Richard Averitt
UC San Diego

TBA



November 14, 2024 Thursday 11:00 AM  +
726 Broadway, Room 1067
Center for Quantum Information Physics Seminars (cqip)


Dirk Morr
University of Illinois Chicago

TBA