IQIM Postdoctoral and Graduate Student Seminar

Friday, May 26, 2023
12:00pm to 1:00pm
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East Bridge 114
A Chiral Light-matter Interface with Superconducting Qubits
Chaitali Joshi, AWS Quantum Postdoctoral Scholar, Mirhosseini Group,


Chiral light-matter interfaces, where photons are emitted directionally into a waveguide, can enable applications such as quantum networks with all-to-all qubit connectivity and investigation of many-body dynamics in cascaded quantum systems. Superconducting circuits have proved to be a powerful platform for studying light-matter interactions within the paradigm of waveguide quantum electrodynamics. However, developing an efficient and scalable chiral interface in this platform has remained elusive.  

In this talk, I will discuss our recent work on realizing a chiral artificial atom using a superconducting qubit operating in the ‘giant atom' regime, where light-matter interaction occurs at a pair of points separated a quarter wavelength apart. The phase of emission is controlled via parametric time-modulated interactions, resulting in interference that leads to unidirectional atom-waveguide coupling. Using this approach, we demonstrate near-perfect chiral emission, with the propagation direction controlled by simple tuning of the relative phase of the parametric couplings. Furthermore, as this method relies on a single qubit as the source of emission, it exhibits robustness against decoherence and manifests quantum nonlinearity under strong drives. We demonstrate this persistence of chirality through resonance fluorescence measurements. Our approach offers a chip-scale, low-loss alternative for realizing non-reciprocal interactions with superconducting quantum circuits without using ferromagnetic materials. This platform can be used for routing quantum information between nodes of a network with complex qubit connectivity and for driven-dissipative stabilization of entanglement in chiral atom arrays. 

Work based on arXiv:2212.11400v1

Lunch will be provided, following the talk, on the lawn north of the Bridge Arcade

Attendees joining in person must demonstrate that they comply with Caltech's vaccination requirements (present Caltech ID or AWS ID or vaccination and booster confirmation).

For more information, please contact Marcia Brown by phone at 626-395-4013 or by email at