# IQIM Postdoctoral and Graduate Student Seminar

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**February 28th** we will host a lightning round seminar, with **three** **10+2 minute talks** (10 minutes of talk and 2 minutes of audience questions). We will have a moderator keeping time (and cutting you off promptly at 10 min - just like in your real talk at APS!).

**Speaker: Alex Buser, Preskill group**

**Title: Quantum Simulation of Quantum Field Theory with Qubit Models**

**Abstract:** Quantum computers are expected to outperform classical methods in the simulation of strongly-coupled quantum field theories, as they permit the calculation of dynamic quantities in real-time and avoid the notorious sign-problem. We consider a class of qubit models which can be simulated efficiently on a fault-tolerant quantum computer, and present evidence that these models possess a rich phase diagram. One of the quantum critical points in the phase diagram may help define the traditional asymptotically free O(3) non-linear sigma model. We discuss implementation of these qubit models on both NISQ and fault-tolerant quantum computers, and provide numerical results on adiabatic ground state preparation for the O(3) sigma model. This work serves as a stepping stone towards simulating non-Abelian Kogut-Susskind type gauge theories with quantum devices.

**Speaker: Tian Xie, Faraon group**

**Title: Study of Erbium doped yttrium orthovanadate crystal for microwave to optical transduction**

**Abstract**: Quantum transduction between the microwave and optical domain is essential for connecting superconducting quantum platforms in a quantum network. Ensembles of rare-earth ions (REIs) coupled to both optical and microwave cavities offer a promising architecture for achieving this conversion because of their collective and coherent properties in the microwave and optical domains. The critical properties of the REI ensemble needed for high transduction efficiency are the optical and microwave transition dipole moments and the optical and spin inhomogeneities.

Erbium ions are of particular interest because they have transitions at telecom wavelengths which allows for the compatibility with optical fiber telecommunication networks. Here, we report the bulk properties of Erbium doped yttrium orthovanadate (Er:YVO) including the Zeeman splitting, optical absorption spectra, oscillator strength and spin inhomogeneity. We also demonstrate proof of concept microwave to optical conversion with a loop gap microwave resonator. The measured strong dipole moment and narrow inhomogeneities point to the Er:YVO as a promising material for quantum transduction.