Since the advent of quantum information science as a theoretical endeavor atomic ions have gained popularity as a natural platform for quantum state engineering. One drawback of the technology is that the process of state detection is inefficient.
The |0> and |1> states of the trapped ion quantum computer can most easily be distinguished by establishing a ‘dark’ state and a ‘bright’ state which can be observed by shining light resonant with the bright state imaging the spontaneous emission events using a PMT. By shining resonant light for a period of time a statistical distribution of photon observations events can be established giving a threshold at which the state is very likely to be bright. If the photon counts are above this threshold then the ion is said to have been observed as ‘bright’
By increasing the collection efficiency of the optical system, and the detection efficiency of the detectors great improvements can be made to this state detection time. Increasing light collection efficiencies can improve the entanglement generation rate, gate fidelities, and execution time of the system.
A two-level system interacting with a resonant optical cavity is a natural experimental platform for the control of atomic light emission. By tuning both the position of that atom within the cavity and using a small volume optical cavity the field intensity interacting with the ion can be greatly increased. This can cause enhanced rate of spontaneous emission as well as the ability to channel most emitted photons into the cavity decay channel, which provides spatial confinement of the light field.
We have developed an in-house fabrication process for carbon dioxide laser ablated micromirror substrates with a radii of curvature in the 300 μm - 1 mm range. Which we are currently testing alone before integration into our ion-trap system.
EPICS (Extreme-Performance Ion trap-Cavity System for Qubit State Detection)
The EPICS program is an ARO funded project to increase, by orders of magnitude, the current speed of ion-trap qubits by utilizing the cavity-ion interaction with an integrated SNSPD optical detector close to the trapping location. This will be a cryogenic trapping experiment to accommodate the low operating temperature requirements of the SNSPD detectors.