Hartmut Haeffner, University of California, Berkeley
Abstract
Trapped atomic ions as well as Josephson-junction devices belong to the most promising avenues towards scalable quantum information processing. Each approach has its unique strengths: while trapped ions can be very well isolated from the environment and have shown to hold quantum information on the second or even on the minute time scale, Josephson junction devices couple very strongly and thus allow for gate speeds of a 100 MHz. On the downside, interactions between trapped ions cannot easily be pushed beyond two-qubit gate speeds of 1 MHz, while at this time the memory capabilities of superconducting devices are limited to about 100 μs. Quantum hybrid devices, where atomic particles are coherently coupled to superconducting circuits, could combine the advantage of strong coupling of superconducting devices with the excellent quantum memory capabilities of trapped atomic particles.
In this talk, I will describe a general strategy towards a quantum hybrid device by interfacing the motion of trapped ions or electrons with superconducting circuits. In such a device, the quantum motion of a charged particle induces a current in nearby trap electrodes which then can be send to a superconducting device. I will discuss the feasibilty of observing this current and show how a single laser cooled trapped ion could cool the resonant mode of a superconducting LC-circuit. We will conclude with a specific scheme on how to couple the motion of trapped electrons in the 100 MHz regime coherently to actual superconducting Josephson-devices in the GHz regime, leading up to a novel quantum computing architecture.