Helmut Fedder

Electric-field sensing using single diamond spins.

The ability to sensitively detect charges under amb ient conditions would be a fascinating new tool benefitting a wide range of researchers ac ross disciplines. However, most current techniques are limited to low-temperature methods l ike single-electron transistors (SET)[1,2], single–electron electrostatic force microscopy[3] a nd scanning tunnelling microscopy [4]. Here we open up a new quantum metrology technique demons trating precision electric field measurement using a single nitrogen-vacancy defect entre(NV) spin in diamond. An AC electric field sensitivity reaching ~ 140V/cm/ √Hz has been achieved. This corresponds to the electric field produced by a single elementary char ge located at a distance of ~ 150 nm from our spin sensor with averaging for one second. By caref ul analysis of the electronic structure of the defect centre, we show how an applied magnetic fiel d influences the electric field sensing properties. By this we demonstrate that diamond defct centre spins can be switched between electric and magnetic field sensing modes and ident ify suitable parameter ranges for both detector schemes. By combining magnetic and electri c field sensitivity, nanoscale detection and ambient operation our study opens up new frontiers in imaging and sensing applications ranging from material science to bioimaging.

Single-Shot Readout of a Single Nuclear Spin

Probed But Not Perturbed The processing and manipulation of quantum information holds great promise in terms of outperforming classical computers and secure communication. However, quantum information is delicate, and even reading the information is a destructive and probabilistic process requiring a number of measurements to home in on the information stored as a quantum state. For the nitrogen vacancy in diamond, Neumann et al. (p. 542, published online 1 July) show that these limitations can be eliminated. A measurement protocol was designed and implemented where the spin state of the nuclear spin of the vacancy could be mapped onto and read out from the surrounding electronic spins in a single-shot measurement nondestructively. The quantum state of a single nitrogen vacancy in diamond can be read out nondestructively in a single-shot measurement. Projective measurement of single electron and nuclear spins has evolved from a gedanken experiment to a problem relevant for applications in atomic-scale technologies like quantum computing. Although several approaches allow for detection of a spin of single atoms and molecules, multiple repetitions of the experiment that are usually required for achieving a detectable signal obscure the intrinsic quantum nature of the spin’s behavior. We demonstrated single-shot, projective measurement of a single nuclear spin in diamond using a quantum nondemolition measurement scheme, which allows real-time observation of an individual nuclear spin’s state in a room-temperature solid. Such an ideal measurement is crucial for realization of, for example, quantum error correction protocols in a quantum register.

Coherent control of single spins in silicon carbide at room temperature

Spins in solids are cornerstone elements of quantum spintronics. Leading contenders such as defects in diamond or individual phosphorus dopants in silicon have shown spectacular progress, but either lack established nanotechnology or an efficient spin/photon interface. Silicon carbide (SiC) combines the strength of both systems: it has a large bandgap with deep defects and benefits from mature fabrication techniques. Here, we report the characterization of photoluminescence and optical spin polarization from single silicon vacancies in SiC, and demonstrate that single spins can be addressed at room temperature. We show coherent control of a single defect spin and find long spin coherence times under ambient conditions. Our study provides evidence that SiC is a promising system for atomic-scale spintronics and quantum technology.

Dynamical decoupling of a single-electron spin at room temperature

Here we report the increase of the coherence time T

Monolithic diamond optics for single photon detection.

_2

Extending spin coherence times of diamond qubits by high-temperature annealing

of a single electron spin at room temperature by using dynamical decoupling. We show that the Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence can prolong the T

Theory of the ground-state spin of the NV- center in diamond

_2

Readout and control of a single nuclear spin with a metastable electron spin ancilla

of a single Nitrogen-Vacancy center in diamond up to 2.44 ms compared to the Hahn echo measurement where T

Microscopic diamond solid-immersion-lenses fabricated around single defect centers by focused ion beam milling

_2 = 390 \mu

Towards T1-limited magnetic resonance imaging using Rabi beats

s. Moreover, by performing spin locking experiments we demonstrate that with CPMG the maximum possible