R. G. Herb Condensed Matter Seminars |
Events During the Week of December 7th through December 14th, 2014
Monday, December 8th, 2014
- No events scheduled
Tuesday, December 9th, 2014
- No events scheduled
Wednesday, December 10th, 2014
- No events scheduled
Thursday, December 11th, 2014
- Probing the Materials Origins of Decoherence in Superconducting Qubits
- Time: 10:00 am
- Place: 5310 Chamberlin Hall
- Speaker: Dr. Vincenzo Lordi, Lawrence Livermore Lab
- Abstract: The practicality of superconducting qubits for scalable quantum computing applications is limited by decoherence noise that reduces the useful lifetime of the quantum states. While various theories explain possible mechanisms for the decoherence, the microscopic origins at the level of the materials comprising actual devices remain largely unknown. Such knowledge is essential to enabling rational improvement of fabrication processes for higher performing qubits. First-principles simulations at the atomic level provide a useful tool to probe the materials origins of decoherence. Here, we discuss recent work investigating magnetic fluctuators associated with materials defects that can contribute decoherence noise in these systems. In particular, native defects and adsorbates on the surface of sapphire and dangling bond defects on the surface of amorphous silica will be discussed. In addition, interactions among spins on surfaces can be important, and we present detailed calculations on the energetics of such interactions. We find that the spin-spin coupling strength can be strongly influenced by lattice strain and the presence of defects. Finally, an analysis of the correlations between local structural and electronic properties of amorphous materials will be presented in this context.
- Host: McDermott
Friday, December 12th, 2014
- Strong, Engineered Photon/Spin Qubit Coupling
- Time: 10:00 am
- Place: 5310 Chamberlin Hall
- Speaker: Alex Rimberg, Dartmouth
- Abstract: Spin qubits, due to their long coherence times, offer great promise for use in quantum computation. At the same time, rapidly manipulating, reading out, and coupling such qubits over long distances remain experimental challenges. In this talk I will discuss a scheme that uses a Cooper pair transistor to induce a strong, engineerable coupling between a spin qubit and photons in a superconducting microwave cavity. This scheme offers the potential to both read out and manipulate a spin qubit using only one to a few cavity photons.
- Host: Eriksson