The most promising hardware modality for quantum information processing (QIP) is based on superconducting Josephson junctions (JJ). We have improved the performance of JJ-qubit devices tremendously during the last few years, but are not yet approaching the limit of what is feasible considering what we know about the JJs´ intrinsic losses. I will develop a new type of superconducting qubit - the *metastable flux qubit* - with extremely small couplings to its various noise sources, and therefore a projected much-improved energy-relaxation time. This would allow for tens of thousands of quantum-logic operations on the qubit. The realization of this device will greatly facilitate the progress towards QIP, and reduce the amount of resource overhead needed for quantum error correction during quantum computation on an entangled multi-qubit system. The novel component going into this qubit is a *superinductance,* shunting the qubit´s non-linear JJ with an impedance greater than the quantum resistance (6.5 kohm). This is hard to achieve with ordinary, geometric (electromagnetic) inductors, whose impedance is always below that of free space (377 ohms), due to unavoidable shunt capacitance. Instead, I intend to use the huge kinetic inductance of superconducting thin-film nanowires. I will make these inductors by sputter deposition of Nb or NbN thin films, and then make metastable flux qubits, with the aim to build up a capability for multi-qubit experiments.
Forskare vid Chalmers, Microtechnology and Nanoscience (MC2), Quantum Device Physics
Doktorand vid Chalmers, Microtechnology and Nanoscience (MC2), Quantum Device Physics
Funding years 2014–2017
Areas of Advance