Special Seminar, Anthony Sigillito, Princeton University, "Electric field control of electronic and nuclear spin qubits in silicon"

Fri, Dec 16, 2016, 12:00 pm to 1:00 pm
Location: 
Jadwin A07
Donor electronic and nuclear spins in silicon form two-level systems with coherence times exceeding seconds, making them promising qubits for quantum computing applications. These spins are typically manipulated using microwave magnetic fields. However, magnetic fields are difficult to confine at the nanoscale, which poses problems when moving beyond the single-qubit system. This talk will focus on overcoming this issue by employing electric fields which are more easily confined. I will first discuss the development of superconducting planar resonators aimed at studying new, more scalable methods for manipulating donor electronic and nuclear spins. I will then show data resolving both spin-orbit and hyperfine Stark effects for 31P donors in silicon. Finally, I will share new, unpublished data demonstrating for the first time electrically driven nuclear magnetic resonance for neutral 31P donor spins in silicon. This mechanism is based on modulation of the electronic orbital states, which in turn leads to an anisotropic hyperfine coupling. Upon extending our measurements to 75As donors, we find a two order-of-magnitude enhancement in the nuclear Rabi frequencies which we attribute to direct modulation of the nuclear quadrupolar interaction. Based on these measurements, we expect that Rabi frequencies of MHz are achievable before donor ionization sets in. If time permits, we will discuss the extension of this technique to donor spins in germanium, another system with long coherence times. Our recent measurements in germanium show a four order-of-magnitude enhancement in the spin-orbit Stark shift which should allow for electrically driven spin resonance of both the electronic and nuclear spins