Cavity enhanced spin measurement of the ground state spin of an NV center in diamond

Abstract

We propose a high efficiency high fidelity measurement of the ground state spin of a single NV center in diamond, using the effects of cavity quantum electrodynamics. The scheme we propose is based in the one dimensional atom or Purcell regime, removing the need for high Q cavities that are challenging to fabricate. The ground state of the NV center consists of three spin levels 3 A (m=0) and 3 A (m=±1) (the ±1 states are near degenerate in zero field). These two states can undergo transitions to the excited ( 3 E) state, with an energy difference of ≈ 6 − 10 µeV between the two. By choosing the correct Q factor, this small detuning between the two transitions results in a dramatic change in the intensity of reflected light. We show the change in reflected intensity can allow us to read out the ground state spin using a low intensity laser with an error rate of ≈ 7×10 −3 , when realistic cavity and experimental parameters are considered. Since very low levels of light are used to probe the state of the spin we limit the number of florescence cycles, thereby limiting the non spin preserving transitions through the intermediate singlet state 1 A.

Photonic Crystal Coupled to N-V Center in Diamond

“…In order to estimate V ef f we used a procedure shown in Ho et al (2011) which creates different frequency snapshots at different position in the computational grid during the simulation, recording all the information of the electromagnetic field in each slice. Using this method and the structure depicted in Fig.12 we estimate the modal volume of the field inside the photonic crystal to be V ef f = 0.0162µm 3 which is a value close to the one we assumed on our work on non-demolition measurement, described in Young et al (2009), and is also consistent with results obtained by other groups as for example Tomljenovic-Hanic et al (2009). The modal volume can be normalized to the cubic wavelength of the resonant mode ( of refractive index (n) defined as:…”

“…The state of NV − center ground state spin strongly modulates the rate of spontaneous emission from the 3 E ↔ 3 A sub-levels providing a mechanism for spin read out as discussed by Hanson et al (2006). We have recently shown theoretically (Young et al (2009)) that spin readout with a small number of photons could be achieved by placing the NV − centre in a subwavelength scale micro-cavity with a moderate Q-factor(Q ∼ 3000). So one of our aims is to optimize the output coupling of photons from diamond color centers into waveguides and free space to increase the efficiency of single photon sources and to enable faster single spin read-out.…”

“…In order to have strong coupling we need to have a cavity with high Q factor and small modal volume, but a cavity with a more moderate Q would still be useful. In particular, a scheme for reading out the ground state spin of an NV − center has been described by our group (Young et al (2009)), that requires a Q (before coupling) of only ∼ 3000. This scheme exploits the zero-field splitting in the NV − center ground state and uses narrow band resonant excitation to achieve high-fidelity read-out of the ground state spin with just a few excitation cycles.…”

Coherent spin control of a nanocavity-enhanced qubit in diamond

“…These systems enable coherent spin control of cavity-coupled semiconductor qubits with coherence times exceeding 200 ms -an increase by 2 orders of magnitude over previously reported cavity-coupled solid-state qubits 8,18,19 . Such systems with specific NV-cavity coupling parameters can also be used for high-fidelity readout due to the modification of spin dynamics of cavity-coupled NVs 25 . Our on-chip architecture could be used to efficiently scale NV-nanocavity systems to many quantum memories connected via photons [26][27][28][29] .…”

One- and two-dimensional photonic crystal microcavities in single crystal diamond

“…Such transfer of quantum information between spins and photons in solid state systems [4] can be strongly enhanced by optical microcavities with small mode volume V mod and large quality factor Q. Micro-cavities can further be employed for enhancing the emission rate of single photon emitters [5,6] based e.g. on NV − centres [7] or bright Cr-related complexes [8] and silicon-vacancy (SiV) centres [9], for cavity enhanced spin measurements [10] and quantum communication [11]. For all these schemes it is important to selectively enhance the zero phonon line (ZPL) emission and suppress emission into phonon side-bands and non-radiative decay channels.…”