Speaker: Olivier Buisson
Affiliation: Institut Néel, CNRS (Grenoble)
Date: Tuesday, 21 June 2016 at 13:00
Location: Seminar Room, Serrano 121 (CFMAC)
We present an experimental study on two superconducting
transmon qubits coupled via a large inductance [1]. The resulting
circuit exhibits a symmetric and an antisymmetric oscillation [2]
which we use as a transmon and ancilla qubit, respectively.We observe
a cross-anharmonicity between the two oscillations which is explained
by the Josephson nonlinearity [1].This coupling leads the artificial
atom to a have V-shape energy diagram.
We have predicted that such V-shape artificial atom, inside a circuit
cavity quantum electrodynamics architecture, allows to read out the
transmon qubit state by using the ancilla qubit frequency [3].
In comparison with the most widely employed readout scheme for
superconducting qubits, the dispersive readout, our approach promises
a quantum non-demolition measurement with a significantly stronger
measurement signal and without suffering from Purcell effect. In a
measurement chain based on a state-of-the-art Josephson parametric
amplifier, we predict a QND fidelity of up to 99.9% for a measurement
time down to 60 ns [3].
[1] É. Dumur, et al, “A V-shape superconducting artificial atom based
on two inductively coupled transmons”, Phys. Rev. B 92, 020515 (2015).
[2] F. Lecocq, et al, “Coherent Frequency Conversion in a
Superconducting Artificial Atom with Two Internal Degrees of
Freedom”, Physical Review Letters 108, 107001 (2012).
[3] I. Diniz, et al, “Ultrafast quantum nondemolition measurements
based on a diamond shaped artificial atom”, Physical Review A 87, 033837 (2013).