11am - 12pm Wednesday 10th October
Materials & Analytical Sciences 2.06

Nitrogen vacancy centres (NVC) in diamond are excellent quantum bits which has led to research into quantum technology (particularly magnetometry [1] and quantum computing [2]) as well as new insights into quantum physics such as a loophole-free violation of Bell’s inequalities [3]. We have proposed [4-7] and begun building [8-10] an experiment that would use a single NVC in a nanodiamond to try and make the most macroscopic superposition ever: we want to create Schrödinger’s kittens. Probing this quantum-to-classical boundary could solve the measurement problem in quantum mechanics: why does the Schrödinger equation sometimes stop working to be replaced by a measurement? Our experiments for this use nanodiamonds levitated in vacuum using optical tweezers, which were pioneered by 2018 Nobel Prize winner Arthur Ashkin.

In other experiments, with single NVC, we have shown that laser-written NVC can have spin coherence times that are as long as naturally occurring NVC [11-13] and deep enough for solid immersion lenses to be made around them. We hope to eventually use these for quantum computing [2].

Finally, we have developed a sensitive fibre-coupled magnetometer from an ensemble of NVC which we will use to search for the magnetic signals given off by our hearts [14] as it is known that magnetocardiography can be useful for medical diagnosis [15].

[1] L. Rondin et al., Rep. Prog. Phys. 77, 056503 (2014).
[2] S.D. Barrett and P. Kok, Phys. Rev. A 71, 060310 (2005).
[3] B. Hensen et al., Nature 526, 682 (2015).
[4] M. Scala et al., Phys. Rev. Lett. 111, 180403 (2013).
[5] C. Wan et al., Phys. Rev. A 93, 043852 (2016).
[6] C. Wan et al., Phys. Rev. Lett. 117, 143003 (2016).
[7] S. Bose et al., Phys. Rev. Lett. 119, 240401 (2017).
[8] A.T.M.A. Rahman et al., Sci. Rep. 6, 21633 (2016).
[9] A.T.M.A. Rahman, A.C. Frangeskou, P.F. Barker and G.W. Morley, Rev. Sci. Instrum. 89, 023109 (2018).
[10] A.C. Frangeskou et al., New J. Phys. 20, 043016 (2018).
[11] Y.-C. Chen et al., Nat. Photon. 11, 77 (2017).
[12] Y.-C. Chen et al., arXiv:1807.04028 (2018).
[13] C.J. Stephen et al., arXiv:1807.03643 (2018).
[14] M.W. Dale and G.W. Morley, arXiv:1705.01994 (2017).
[15] R. Fenici, D. Brisinda and A.M. Meloni, Expert Rev. Mol. Diagn. 5, 291 (2005).