Theta oscillations underlie retrieval success effects in the nucleus accumbens and anterior thalamus: Evidence from human intracranial recordings

Spin properties of NV centers in high-pressure, high-temperature grown diamond

“…For the plates we examined, the maximum concentration of p 1 centers measured by the infrared spectroscopy method reached 68 ± 17 ppm. For these plates, the coherence time measured was 3.2 ± 0.6 μs and 3.7 ± 0.3 μs which is, slightly better than the 2.4 ± .6 μs limit [11]. While there is slight difference, within 2σ these results are consistent.…”

“…This limit in principle could be further reduced by increasing conversion efficiency of nitrogen to NV − . At low nitrogen concentrations, coherence time seems to approach the limit caused by the presence of 13 C observed by the other groups [11]. Thus, flattening of the figure 4(A) at low concentration is quite expected and only could be overcome using isotopically pure diamonds.…”

“…In the case of AC magnetometer, similar behavior could be observed ( figure 4(B)). High nitrogen concentrations in the case of CVD plates was shown in a paper [11] to have limit for coherence time of T 2 = 165 μs·ppm/n N , where n N is the concentration of p 1 centers. For the plates we examined, the maximum concentration of p 1 centers measured by the infrared spectroscopy method reached 68 ± 17 ppm.…”

“…The next factors affecting the width of the ODMR resonance are its interaction with 13 C having nuclear spin and being normally present in diamonds with a natural abundance of carbon [16], and p 1 defects that have electron spin on donor nitrogen [12,13]. The 13 C effect represents a fundamental limitation for coherence time that cannot be overcame unless isotopically pure diamond is used [11]. The influence of defects on coherence dominates at high nitrogen concentrations and strongly depends on nitrogen-to-NV conversion efficiency.…”

“…Finding the optimal balance between concentration and coherence time of NV centers requires careful optimization of diamond growing and post-processing procedures. In this work, we demonstrate that properly post-processed diamond grown by the high-pressure, high-temperature (HPHT) method, could demonstrate coherence time limited by either interaction with 13 C at a low concentration of nitrogen [11], or by interaction with nitrogen electron spins of so-called p 1 centers in the case of large nitrogen concentrations [12,13].…”