R. G. Herb Condensed Matter Seminars |
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
Wednesday, April 20th, 2016
- No events scheduled
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
Friday, April 22nd, 2016
- No events scheduled