Abstract:
Combining superconducting circuits with mesoscopic devices that enable non-local encoding with Majorana quasi-particles can lead to compact and improved qubit devices with properties useful for fault-tolerant quantum computation [1,2,3]. Here we discuss a complementary approach to describe how protected qubit states could also emerge in a small chain of superconducting qubits and resonators. This is achieved by considering local Heisenberg spin interactions supplemented by long range interactions. A phase with two quasi-degenerate ground states which are highly protected against all local field perturbations is found and analysed [4]. This architecture can also be used to observe signatures of topological edge states in a small controlled chain of superconducting transmon qubits. The architecture of such a device, resilience of the logical states against disorder, scalability and controllability will be discussed.
References:
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[2] Microwave transitions as a signature of coherent parity mixing effects in the Majorana-transmon qubit, Eran Ginossar and Eytan Grosfeld, Nature Communications 5, 4772 (2014)
[3] Fermion parity measurement and control in Majorana circuit quantum electrodynamics, Konstantin Yavilberg, Eran Ginossar, Eytan Grosfeld, Phys. Rev. B 92, 075143 (2015)
[4] Protected ground states in short chains of coupled spins in circuit quantum electrodynamics, Adam Callison, Eytan Grosfeld, Eran Ginossar, Phys. Rev. B 96, 085121 (2017)