From supersensitive detections of magnetic fields to quantum information processing, the key to a number of highly promising advanced technologies may lie in one of the most common defects in diamonds. Researchers have taken an important step towards unlocking this key with the first ever detailed look at critical ultrafast processes in these diamond defects.

Using two-dimensional electronic spectroscopy on pico- and femto-second time-scales, a research team has recorded unprecedented observations of energy moving through the atom-sized diamond impurities known as nitrogen-vacancy (NV) centers. An NV center is created when two adjacent carbon atoms in a diamond crystal are replaced by a nitrogen atom and an empty gap.

These 2D electronic spectroscopy measurements have provided us with the first window into the ultrafast dynamics of NV centers in diamond,” says Huxter. “We were able to observe previously hidden vibrational and electronic properties of the NV center system, including the discovery of vibrational coherences lasting about two picoseconds, which on a quantum mechanical scale is a surprisingly long time.”

Given the ubiquitous presence of weak magnetic fields, a sufficiently sensitive detector could be used in a wide range of applications including medical diagnostic and treatment procedures, chemical analyses, energy exploration and homeland security (to detect explosives). Diamond NV centers are held to be one of the finest magnetic sensors possible on the nanoscale. Diamond NV centers are also highly promising candidates for the creation of qubits – data encoded through quantum-spin rather than electrical charge that will be the heart and soul of quantum computing. Qubits can store exponentially more data and process it billions of times faster than classical computer bits. However, for these rich promises to be fully met, a much better fundamental understanding is needed of the electronic-state dynamics when an NV center is energized.

This study was made possible by the unique 2D electronic spectroscopy technique, which was first developed by Fleming and his research group to study the quantum mechanical underpinnings of photosynthesis. This ultrafast technique enables researchers to track the transfer of energy between atoms or molecules that are coupled (connected) through their electronic and vibrational states. Tracking is done through both time and space. It is accomplished by sequentially flashing light from three laser beams on a sample while a fourth beam serves as a local oscillator to amplify and phase-match the resulting spectroscopic signals.

In this new study, the use of 2D electronic spectroscopy revealed that the vibrational modes of NV centers in diamond – a subject of keen scientific interest because these modes directly affect optical and material properties – are strongly coupled to the defect.

In addition, the researchers also were able to measure non-radiative relaxation in the excited state, a property that must be understood and exploited for the creation of qubits.

The information acquired from this study should make it possible to tune the properties of NV centers in diamonds and open up new avenues for research.

This story is reprinted from material from
Berkeley Lab, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.