Subpicotesla Diamond Magnetometry

Abstract

NV defect centres in diamond are promising solid-state magnetometers. Single centres allow for high spatial resolution field imaging but are limited in their magnetic field sensitivity to around 𝟏𝟎 𝐧𝐓/√𝐇𝐳 at room temperature. Using defect centre ensembles sensitivity can be scaled as √𝑵 when 𝑵 is the number of defects. In the present work, we use an ensemble of 10 11 defect centres for sensing. By carefully eliminating all noise sources like laser intensity fluctuations, microwave amplitude and phase noise we achieve a photon shot noise limited field sensitivity of 𝟎. 𝟗 𝐩𝐓/√𝐇𝐳 at room-temperature with an effective sensor volume of 𝟖. 𝟓𝐞-𝟒 𝐦𝐦 𝟑 . The smallest field we measured with our device is 𝟏𝟎𝟎 𝐟𝐓. While this denotes the best diamond magnetometer sensitivity so far, further improvements using decoupling sequences and material optimization could lead to 𝐟𝐓/√𝐇𝐳 sensitivity.

Enhanced concentrations of nitrogen-vacancy centers in diamond through TEM irradiation

“…While this realistic scheme is expected to be limited in terms of the resulting NV-NV interaction strength, with the use of proper dynamical decoupling protocols [13], the NV-NV interactiondominated regime could still be reached. Moreover, the resulting enhancement in the conversion efficiency could make NV ensemble sensors vastly smaller and therefore more practical for magnetic [1,3,7], thermal [8], and electric [9] sensing. TEM electron irradiation can also be used to create spin-active defects in other solid-state systems, such as silicon carbide [22].…”

“…In addition to the fundamental understanding of spin dynamics, such research could pave the way toward the demonstration of non-classical spin states, which will be useful for a variety of applications in quantum information and quantum sensing. One of the leading candidates for such studies is the negatively charged nitrogen-vacancy (NV) center in diamond, having unique spin and optical properties, which make it useful for various sensing applications [1][2][3][4][5][6][7][8][9], as well as a resource for quantum information processing and quantum simulation [10][11][12].…”

Autonomous calibration of single spin qubit operations

“…3,4 Its remarkable features, such as optical initialisation and readout, and the ability to be manipulated by microwave fields at room temperature, make this physical system extremely attractive for many quantum technologies. 5 We have witnessed a vast array of demonstrations of the NV centres showing a great potential for future technologies, ranging from sub pico-Tesla magnetometry, 6 electric field and temperature sensing, 7,8 to probing molecular dynamics, 9 and single-cell magnetic imaging. 10 Furthermore, intertwinements between quantum information and metrology using NV centre-based systems yield novel and effective techniques towards the realisation of high-performance technologies, e.g.…”

Detection of a weak magnetic field via cavity-enhanced Faraday rotation

“…Magnetic fields can be measured using a variety of techniques including a superconducting quantum interference device (SQUID) [1], magneto-materials [4], atoms [5][6][7][8] and color defect centres in diamond [9][10][11]. The SQUID magnetometers achieve record sensitivities [1], but require extremely low temperatures to maintain superconductivity [1].…”

“…Recently, atomic magnetometers have demonstrated subfemtotesla sensitivity, approaching the record sensitivity of SQUID sensors [6][7][8]. Diamond magnetometers exploiting nitrogen vacancy (NV) defect centres in diamond offers detection of magnetic field signals both with high spatial accuracy [12][13][14][15] as well as high field sensitivity down to sub-pT/ √ Hz [9,11]. In this work, we describe a magnetometer approaching sub-fT/ √ Hz sensitivity with nW-order input power that exploits the Faraday rotation of microwave (mw) photons induced by a static magnetic field.…”