Buidling a room temperature quantum computing grid

Public interest in quantum technology is fueled by the vision of a quantum computer. The shift to having a grid of low-cost, scalable room-temperature quantum memories and gates will make a light-based quantum computer... [ view full abstract ]

Public interest in quantum technology is fueled by the vision of a quantum computer. The shift to having a grid of low-cost, scalable room-temperature quantum memories and gates will make a light-based quantum computer practical and economically feasible. While computational improvements through quantum computation are very promising, building a useful quantum computer is challenging because of the all-or-nothing nature of quantum supremacy. In this presentation we discuss our progress towards building large arrays of room-temperature quantum light-matter interfaces.

The basis of this quantum grid are room-temperature quantum light-matter interfaces. We have demonstrated complete quantum memory operation for polarization qubits with average fidelities > 99% and the potential to operate with hundred micro-second lifetimes and 50% storage efficiency [1]. These systems can also be used for single photon-level triggered phase-shifts operations at room temperature. We have characterized the quantum state of pi-phase-shifted single-photon-level pulses in a double lambda closed-loop system. For particular choices in control field strength and input phase, the fidelity of the reconstructed quantum state can reach higher than 90% while having a pi-radians phase shift with respect to an original reference [2].

Furthermore, we have used our quantum light-matter interfaces to implement an analog simulator of relativistic and topological physics. We have realized the Jackiw-Rebbi model (JR). Our system was based upon interacting dark state polaritons (DSPs) created by storing light in a rubidium vapor using a dual-tripod atomic system. We also probed the obtained topologically protected zero energymode by analyzing the time correlations between the spinor components. The DSPs temporal evolution emulates the physics of Dirac spinors and is engineered to follow the JR regime by using a linear magnetic field gradient [3].

Finally, we are currently scaling the number of qubits addressable within the room-temperature system. We have engineered a 36-rails light grid using rubidium tuned light in the form of single photon level pulses. We have performed single-photon sensitive imaging of this light grid using a Tpx3Cam, allowing time and spatial stamping of incident photons. We will present preliminary results on the characterization of a grid of 36 quantum memories within a single rubidium cell. We will also discuss the envisioned functionalities of the quantum grid as an analog quantum simulator of molecular dynamics and as a multi-qubit one-way quantum processing unit.

[1] Phys. Rev. Applied 8, 034023 (2017).

[2]  arXiv:1803.07012 (2018).
[3]  arXiv:1711.09346 (2017).