Quantum control in the solid-state

High precision quantum sensing, secure communication, and quantum information processing all rely on a perfect understanding and control of a quantum system. Using an ensemble quantum system as a coherent controllable system offers enhanced sensitivity and fidelity, however understanding its collective effects and stabilizing the surrounding disturbances is still an active challenge [1].

[1] Choi, Soonwon, Norman Y. Yao, and Mikhail D. Lukin. “Quantum metrology based on strongly correlated matter”, arXiv:1801.00042 (2018).

 

Research projects

Many-body physics and cooperative effects in nanodiamonds

Description: One particular ensemble quantum system that we are investigating is collections of Nitrogen Vacancy (NV) centres in diamond. It is a naturally occurring, photostable and bio compatible quantum material that allows polarization and readout of the internal spin states by optical means at ambient conditions [1]. As a single photon source, the NV centre can be coherently controlled and manipulated using Microwaves and has experimentally demonstrated as a stable qubit at room temperature. As an ensemble of NV emitters in nanodiamond, we have observed intrinsic cooperativity such as superradiance [2]. The observation of intrinsic superradiance shows the increased complexities of using ensemble emitters whilst also showing the possible benefits after gaining more systematic control over it. Ultimately we want to achieve deterministic control over an NV ensemble to use it as a single system offering enhanced sensitivity and readout signal [3].

[1] M.W. Doherty et al. “The nitrogen-vacancy colour centre in diamond.” Physics Reports 528.1 (2013).

[2] C. Bradac et al. “Room-temperature spontaneous superradiance from single diamond", Nature communications 8 (1), 1-6 (2017).

[3] MT Johnsson et al., "Scalable preparation of Dicke states for quantum sensing", arXiv preprint arXiv:1908.01120 (2019).

Contact: Jemy Geordy, Lachlan Rogers, Thomas Volz

Diamond based MASER

Description: We are working towards the construction of a MASER (microwave amplification by stimulated emission of radiation) using nitrogen vacancy (NV) centres in diamonds and nanodiamonds. By manipulating the NV centres using magnetic fields, and optically pumping a preferential level of the triplet spin state, we can generate the population inversion required for masing (the microwave equivalent of lasing). The ensemble of NV centres can then be coupled to a microwave cavity to allow maser action. By adjusting the magnetic field strength and the cavity resonance we can tune the maser frequency arbitrarily. This has potential applications as a solid-state low noise microwave amplifier, a new form of accurate clock, and high sensitivity magnetometry.

Contact: Lyra Cronin, Lachlan Rogers, Thomas Volz

 
 
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