Strongly Coupled Multi-Qubit Systems Using Superconducting Quantum Circuits
Storing and processing information using quantum two level systems (qubits) promises tremendous speed-up for certain computational tasks like finding prime factors and for simulation of quantum systems. Superconducting electronic circuits operating at millikelvin temperatures have emerged as a leading candidate for building such a quantum processor. One key requirement is controlling and manipulating the interactions between multiple qubits. Rather than using single qubit circuits as building blocks, I will introduce a novel three-qubit superconducting device as an elementary block. The device, nicknamed “trimon”  implements three qubits with pairwise longitudinal coupling. The always-on coupling enables simple implementation of generalized controlled rotations using transition selective pulses. I will describe how to harness the full three-qubit computational space and discuss the implementation of several multi-qubit gates like CNOT and Toffoli gate. I will conclude by discussing possible applications of this device and further extensions to this idea.