A diamond chip contains NV centres at density throughout a sensing volume of ( )

PHYSICS · Multi-part · Fermi University Physics · Quantum Information & Technology · Physical realizations and quantum technologies · Physical realizations and quantum technologies

Quantum Information and Technology, Ch Quantum metrology and sensing

Problem

A diamond chip contains NV centres at density

n = 3\times10^{17}\,\mathrm{cm}^{-3}

throughout a sensing volume of

1\,\mathrm{mm}^3

(

=1\times10^{-3}\,\mathrm{cm}^3

). Each centre has

T_2^* = 1\,\mu\mathrm{s}

and readout efficiency

C = 0.03

, the same parameters as a single centre whose sensitivity is

\eta_B = 0.19\,\mu\mathrm{T}/\sqrt{\mathrm{Hz}}

. ((a)) Estimate the number

N

of NV centres in the sensing volume. ((b)) Treating the centres as independent quantum probes obeying the standard quantum limit's

1/\sqrt{N}

scaling, estimate the ensemble's field sensitivity. ((c)) The best reported ensemble NV sensitivity is about

0.9\,\mathrm{pT}/\sqrt{\mathrm{Hz}}

(Wolf et al., Phys. Rev. X 5, 041001 (2015)). Compare it with the estimate and comment on why they differ.

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