JQI Seminar: Zhifan Zhou and Ryohei Kobayashi

Mon, Nov 27, 2023 11:00 am - 12:00 pm
ATL 2400


Postdoc Talks

Speaker: Zhifan Zhou 

Title: Generation of hypercubic cluster states in 1-4 dimensions in a simple optical system

Abstract: Multi-mode continuous-variable entanglement has become increasingly important for practical quantum information processing. We generate 2-mode vacuum-squeezed optical states through a 4-wave mixing (4WM) process in Rb atomic vapor and conduct a detailed study using homodyne measurements. By dividing the squeezing bandwidth into smaller frequency bins, we show that different sideband frequencies represent independent sources of two-mode squeezing. We then mix the different sideband frequencies (frequency qumodes) using an electro-optical modulator (EOM), thereby producing a pattern of entanglement correlations that constitute a continuous-variable graph state that is transformable into a cluster state by
Gaussian local unitary operations. Using a single-frequency EOM drive we correlate neighboring frequency bands within the 4WM squeezing bandwidth, to create a dual-rail 1-D optical cluster state. By driving the EOM with additional frequencies, we create 2-, 3-, and 4-D optical cluster states with hundreds of qumodes and demonstrate the entanglement structure of these as well by verifying that the state nullifier variances return values close to the original squeezing levels.

Speaker: Ryohei Kobayashi

Title: Non-Clifford logical gates of (3+1)D fermionic Z2 toric code from pumping topological states

Abstract: We consider the logical gate of (3+1)D Z2 gauge theory with an emergent fermionic particle, and point out that pumping the p+ip topological state through the 3d space defines the emergent Z8 global symmetry. We then show that in the context of stabilizer quantum codes, one can obtain logical CCZ and CS gates by placing the code on a discretization of T^3 (3-torus) and mapping torus of T^2 respectively, and pumping p+ip states. Our considerations also imply the possibility of a logical T gate by placing the code on RP3 and pumping a p+ip topological state.

*You will need to bring your cell phone, so you can sign in using the flowcode.  For Zoom, please submit a chat saying hello with your first and last name, so you can receive lunch.  Lunch will be served after the seminar only to the individuals that have attended.*