R. G. Herb Condensed Matter Seminars

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Events During the Week of April 17th through April 24th, 2016

Monday, April 18th, 2016

No events scheduled

Tuesday, April 19th, 2016

Semiconductors for Superconducting Qubits
Time: 10:00 am
Place: 5310 Chamberlin Hall
Speaker: Karl Petersson, University of Copenhagen
Abstract: We have developed a superconducting transmon qubit with a semiconductor-based Josephson junction element [1,2]. The junction is made from an InAs nanowire with in situ molecular beam epitaxy-grown superconducting Al contacts. This gate-controlled transmon, or gatemon, allows simple tuning of the qubit transition frequency using a gate voltage to vary the density of carriers in the semiconductor region. In the first generations of devices we have measured coherence times up to 10 µs. These coherence times, combined with stable qubit operation, permit single qubit rotations with fidelities of ~99.5% for all gates including voltage-controlled Z rotations. Towards multi-qubit operation we have also implemented a two qubit voltage-controlled cPhase gate. In contrast to flux-tuned transmons, voltage-tunable gatemons may simplify the task of scaling to multi-qubit circuits and enable new means of control for many qubit architectures.

[1] T. W. Larsen et al., Phys. Rev. Lett. 115, 127001 (2015).
[2] G. de Lange et al., Phys. Rev. Lett. 115, 127002 (2015).
Host: Smith/Coppersmith
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Wednesday, April 20th, 2016

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Thursday, April 21st, 2016

Quantum optics with ultra-cold atoms
Time: 10:00 am - 11:00 am
Place: Chamberlin 5310
Speaker: Alex Kuzmich, University of Michigan
Abstract: The advent of laser cooling thirty years ago enabled studies of properties of ultra-cold atomic gases and led to their applications in metrology and quantum information. Against this backdrop, in the last decade a world-wide effort in using ultra-cold atoms as nonlinear media for single photons has emerged. The near-ideal character of interaction between light and atomic ensembles cooled to micro-Kelvin-scale temperatures permits realization of textbook quantum-optical Hamiltonians while coupling to unwanted environments can be nearly eliminated. In this way ultra-cold atoms have been used for generation of single-photon and entangled light fields, their wavelength conversion and entanglement with atoms, and realization of many-body dynamics and long-term storage of quantum states. Besides offering a rich new system for studying quantum mechanics, these advances may find applications in future information distribution and processing systems.
Host: Saffman
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Friday, April 22nd, 2016

No events scheduled