Abstract

NV centers ensemble have proven to be sensitive and versatile sensor platform for many applications such as magnetometry [1,2], electric field sensing [3], thermometry [4] and rotation sensing [5]. The tradeoff between concentration of NVs and coherence lifetime of the electronic spin limits the maximum sensitivity of such devices. Recently usage of quantum memory associated with nuclear spins nearby NV center was shown to dramatically increase the sensitivity via accumulation of the sensed signal in memory [6]. This way sensing on single NV center can benefit a lot from nearby environment, but extension of this technique on atomic ensemble is still quite challenging. Here we present a versatile platform for quantum manipulation with a highly dense NV ensemble in HPHT diamond plates. In our work, we demonstrate several approaches to initialize quantum memory in regular magnetic fields, manipulation of quantum memory, and reading the quantum information from it. Also, we carefully study decoherence rate in our sample using “Echo” and “FID” techniques. We believe the key sources of decoherence in our samples are natural abundance of ¹³C isotopes and P1 centers. To better understand and clarify contribution of each component we studied number of samples with different defect concentrations. Besides, multifrequency resonances were investigated in NV ensembles both experimentally and theoretically. Previously multifrequency resonances were studied in single NV center system at various combinations of transverse and longitudinal MW and RF field allowing to detect many-photon transitions in electron spin subshell[7]. Here we provide study of additional series of resonances achieved in NV ensemble configuration with a close look to the many-photon transitions both in electron and nuclear eigen states. This resonances could be utilized to hyperpolarize the nuclear spin environment in diamond.

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