Understanding physical quantities at the nanoscale is a frontier research topic that has profound and broad impact covering fundamental physics to emerging technologies. In nanoscale, the material properties manifest their quantum nature; hence a quantum sensor could be advantageous to effectively harness these quantum effects for sensing and precision measurements. In this talk, I will discuss the prospects of spins associated with Nitrogen-Vacancy (NV) centres in diamond for quantum sensing1. This solid-state sensor offers unique advantages for precision measurement of magnetic field2,3, electric field4, temperature and strain under ambient conditions1.
The first part of my talk will focus on applications pertaining to single NV spins. I will outline the developments of an NV spin microscope to probe molecular structure and dynamics of single biomolecules1,2,5. Followed by this, I will present some results on using single NV sensors to probe phase transition at the nanoscale in a liquid-crystalline material6. Here we used a single NV as a dual-mode sensor to probe the nuclear spin fluctuations and temperature simultaneously to obtain information about controlled phase transition of the soft-matter as a function of temperature. Finally, I will detail our approach on a Hybrid quantum sensor that enhances the static-field sensitivity 102 times and reaching nT/√Hz. This scheme could be scaled to achieve another 103 improvements thus being able to detect bio-magnetic fields from cardiac activities in real-time on par with vapour-cell magnetometers. In the second part of my talk, I will discuss our research focus on fibre-based NV sensor for non-local and multiplexed sensing in a highly flexible environment. I will include some key possibilities and proof-of-principle results. These include enhancing the excitation/collection efficiencies of NV rich diamond micro-crystals7, NV defects as a precision optical micro-heater8 and also NV sensor operated in a dual-mode to study demagnetization of micro-magnets9.
Balasubramanian, A. Lazariev, S.R. Arumugam, and D.-W. Duan. Nitrogen- vacancy color center in diamond-emerging nanoscale applications in bioimaging and biosensing. Current Opinion in Chemical Biology, 20(1):69–77, 2014.
Balasubramanian, I.Y. Chan, R. Kolesov, M. Al-Hmoud, J. Tisler, C. Shin, C. Kim, A. Wojcik, P.R. Hemmer, A. Krueger, T. Hanke, A. Leitenstorfer, R. Bratschitsch, F. Jelezko, and J. Wrachtrup. Nanoscale imaging magnetometry with diamond spins under ambient conditions. Nature, 455(7213):648–651, 2008.
Balasubramanian, P. Neumann, D. Twitchen, M. Markham, R. Kolesov, N. Mizuochi, J. Isoya, J. Achard, J. Beck, J. Tissler, V. Jacques, P.R. Hemmer, F. Jelezko, and J. Wrachtrup. Ultralong spin coherence time in isotopically engineered diamond. Nature Materials, 8(5):383–387, 2009.
Dolde, H. Fedder, M.W. Doherty, T. Nöbauer, F. Rempp, G. Balasubramanian, T. Wolf, F. Reinhard, L.C.L. Hollenberg, F. Jelezko, and J. Wrachtrup. Electric-ﬁeld sensing using single diamond spins. Nature Physics, 7(6):459–463, 2011.
Lazariev, S. Arroyo-Camejo, G. Rahane, V.K. Kavatamane, and G. Balasubramanian. Dynamical sensitivity control of a single-spin quantum sensor. Scientiﬁc Reports, 7(1), 2017.
K. Kavatamane, D. Duan, S. Arumugam, N. Raatz, S. Pezzagna, J. Meijer, G. Balasubramanian, “Probing phase transitions in a soft matter system using a single spin quantum sensor.”, New Journal of Physics, 2019.
Duan, G.X. Du, V.K. Kavatamane, S. Arumugam, Y.-K. Tzeng, H.-C. Chang, and G. Balasubramanian. Eﬃcient nitrogen-vacancy centers’ ﬂuorescence excitation and collection from micrometer-sized diamond by a tapered optical ﬁber in endoscope- type conﬁguration. Optics Express, 27(5):6734–6745, 2019.
Duan, V.K. Kavatamane, S.R. Arumugam, G. Rahane, G.-X. Du, Y.-K. Tzeng, H.-C. Chang, and G. Balasubramanian. Laser-induced heating in a high-density ensemble of nitrogen-vacancy centers in diamond and its eﬀects on quantum sensing. Optics Letters, 44(11):2851–2854, 2019.
Duan, V.K. Kavatamane, S. Arumugam, G. Balasubramanian, “Nitrogen-Vacancy centers as a self-gauged micro-scale heater and its application for multi-modal sensing of demagnetization in micro-magnets.”, Optics Express (submitted).