## Q-Farm Quantum Seminar Series presents Two Speakers

**Universal Programmable photonic architecture for quantum information processing**

Ben Bartlett, Stanford University

Photonics provides a range of unique advantages as a platform for quantum information processing, but presents intrinsic challenges which make compact deterministic devices difficult to implement. In this talk, we describe an architecture for a photonic integrated circuit which can be dynamically programmed to implement any quantum operation, in principle deterministically and with perfect fidelity. Our architecture consists of a lattice of beamsplitters and phase shifters, which perform rotations on path-encoded photonic qubits, and embedded quantum emitters, which use a two-photon scattering process to implement two-qubit controlled gates deterministically. We discuss how to program the device and we show how machine learning techniques can be used to automatically implement highly compact approximations to desired quantum circuits.

**Piezo-optomechanical transduction for microwave to optical quantum frequency conversion**

Wentao Jiang, Stanford University

Efficient modulation of the optical properties of a material or a device has long been pursued for both classical and quantum applications. Mechanical deformation strongly perturbs the refractive index compared to other methods and has the potential to be orders of magnitude more energy efficient. In this talk, we compare different approaches for microwave to optical quantum frequency conversion and show how existing optomechanical converters with gigahertz-frequency mechanical mode suffer from some combination of low optical quality factor, low electrical-to-mechanical transduction efficiency, and low optomechanical interaction rate. We consider all these design challenges and demonstrate a piezo-optomechanical converter that combines an efficient piezoelectric transducer with an optimized optomechanical crystal, and improves the conversion efficiency by nearly three orders of magnitude.