Charge State Conversion, Dynamics, and Single Photon Emission from Diamond using High Voltage Nanosecond Pulse Discharge

Single photon emission (SPE) is important for quantum communication and quantum information processing. While SPE from diamond has been studied extensively over the past 20-years, most of these studies have been all-optical (using external pulsed lasers), and there have been relatively few on their electro-optic or optoelectronic effects (excluding microwave excitation).

In order to utilize these quantum emitters in real systems for quantum communication and quantum information processes, some form of electron-based modulation will likely be needed. This project uses high voltage nanosecond pulses (>5kV and <50 nsec) to control the charge state of these defects, which opens up new parameters in the design of practical quantum communication systems. For example, the ability to modulate the emission wavelength of a single quantum emitter can provide an important capability in the optical read-out of these quantum emitters and for encoding quantum information.

Also, there are several key difficulties in producing efficient electrically-driven light emission from diamond, which have greatly limited their potential use in practical applications. These challenges include difficulty injecting charge carriers due to the large Schottky barrier associated with these wide bandgap semiconductors. This project explores several strategies for overcoming these challenges.

Once these challenges have been overcome, diamond pn-junctions may provide a good platform for producing electrically-driven single photons.

This project will explore novel mechanisms of light emission from diamond using high voltage nanosecond pulses (>5kV and <50 nsec). This approach can selectively produce emission from the negatively charged state of silicon-vacancy defects in diamond (i.e., SiV–), which exhibits narrow (FWHM = 4 nm at room temperature) emission at 738 nm, as distinct from the charge neutral state (i.e., SiV0) which emits around 946 nm. This project explores lower defect densities (i.e., single defect emission) than were previously studied, measuring charge-spin coupling (via ODMR), lifetimes and dynamics, and time-correlated single photon counting (TCSPC) measurements.

The project will also explore electroluminescence from diamond pn-junctions, coupling to photonic crystal cavities and waveguides, and scaling these devices down to smaller sizes that operate at lower voltages. High voltage nanosecond pulse discharges enable extremely high peak fields to be achieved with negligible heating, providing an additional degree of freedom in the manipulation of this well-studied quantum emitter.

While manipulation of spin states can be attained easily through magnetic resonance excitation (i.e., electron spin resonance and ODMR), charge state manipulation is not well-established, and techniques for manipulating this important quantum number are lacking. By mapping the luminescence of these devices systematically over a wide range of diamond substrates and voltage pulse parameters, a fundamental understanding of both classical and quantum light emission can be developed, in order to answer several open questions regarding this voltage-induced modulation of the charge state and the emission of Si-vacancy defects in diamond.

The project will provide quantum information science education at various grade levels from elementary school to high school students. In addition, a module devoted to nanoscale classical and quantum optoelectronics will be developed for a new nanoscience course, and the research accomplishments under this grant will be discussed in class and integrated into the curriculum.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.