Quantum Computing Utilizing Microwave Photons

High-precision instrumentation has been shown to measure the arrival of microwave photons sans destroying the quantum information encoded. The Swiss Federal Institute of Technology and University of Tokyo have shown the detection of the photon’s arrival via its cavity-qubit reflection. Though not a completely new concept, use of microwave photons has previously ended with the detected photon destroyed. Enter quantum non-demolition, or QND. With continued research, the end-result could be microwave quantum computing enabled completely by photons. April 23, 2018.

“Quantum non-demolition detection of propagating photons is achieved using a transmon circuit (a superconducting qubit) inside a microwave cavity. The cavity mediates an entangling interaction between the transmon and the propagating microwave field. Here, the reflection of a single photon off the cavity imparts a 180° rotation on the qubit state, which is represented as an arrow in a spherical phase space. The change in the state of the qubit can be determined from a later rotation and projective readout”. (Image Credit: APS/Alan Stonebraker)

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