16 research outputs found
Voltage driven, local, and efficient excitation of nitrogen-vacancy centers in diamond
Magnetic sensing technology has found widespread application in industries as
diverse as transportation, medicine, and resource exploration. Such use cases
often require highly sensitive instruments to measure the extremely small
magnetic fields involved, relying on difficult to integrate Superconducting
Quantum Interference Device (SQUID) and Spin-Exchange Relaxation Free (SERF)
magnetometers. A potential alternative, nitrogen vacancy (NV) centers in
diamond, has shown great potential as a high sensitivity and high resolution
magnetic sensor capable of operating in an unshielded, room-temperature
environment. Transitioning NV center based sensors into practical devices,
however, is impeded by the need for high power RF excitation to manipulate
them. Here we report an advance that combines two different physical phenomena
to enable a highly efficient excitation of the NV centers: magnetoelastic drive
of ferromagnetic resonance (FMR) and NV-magnon coupling. Our work demonstrates
a new pathway to combine acoustics and magnonics that enables highly energy
efficient and local excitation of NV centers without the need for any external
RF excitation, and thus could lead to completely integrated, on-chip, atomic
sensors.Comment: Fixed an issue with the display of figure
A diamond nanophotonic interface with an optically accessible deterministic electronuclear spin register
A contemporary challenge for the scalability of quantum networks is
developing quantum nodes with simultaneous high photonic efficiency and
long-lived qubits. Here, we present a fibre-packaged nanophotonic diamond
waveguide hosting a tin-vacancy centre with a spin-1/2 Sn nucleus. The
interaction between the electronic and nuclear spins results in a signature
452(7) MHz hyperfine splitting. This exceeds the natural optical linewidth by a
factor of 16, enabling direct optical nuclear-spin initialisation with 98.6(3)%
fidelity and single-shot readout with 80(1)% fidelity. The waveguide-to-fibre
extraction efficiency of our device of 57(6)% enables the practical detection
of 5-photon events. Combining the photonic performance with the optically
initialised nuclear spin, we demonstrate a spin-gated single-photon
nonlinearity with 11(1)% contrast in the absence of an external magnetic field.
These capabilities position our nanophotonic interface as a versatile quantum
node in the pursuit of scalable quantum networks
Valley-hybridized gate-tunable 1D exciton confinement in MoSe2
Controlling excitons at the nanoscale in semiconductor materials represents a
formidable challenge in the fields of quantum photonics and optoelectronics.
Achieving this control holds great potential for unlocking strong
exciton-exciton interaction regimes, enabling exciton-based logic operations,
exploring exotic quantum phases of matter, facilitating deterministic
positioning and tuning of quantum emitters, and designing advanced
optoelectronic devices. Monolayers of transition metal dichalcogenides (TMDs)
offer inherent two-dimensional confinement and possess significant binding
energies, making them particularly promising candidates for achieving
electric-field-based confinement of excitons without dissociation. While
previous exciton engineering strategies have predominantly focused on local
strain gradients, the recent emergence of electrically confined states in TMDs
has paved the way for novel approaches. Exploiting the valley degree of freedom
associated with these confined states further broadens the prospects for
exciton engineering. Here, we show electric control of light polarization
emitted from one-dimensional (1D) quantum confined states in MoSe2. By
employing non-uniform in-plane electric fields, we demonstrate the in-situ
tuning of the trapping potential and reveal how gate-tunable
valley-hybridization gives rise to linearly polarized emission from these
localized states. Remarkably, the polarization of the localized states can be
entirely engineered through either the spatial geometry of the 1D confinement
potential or the application of an out-of-plane magnetic field
Hyperfine Spectroscopy of Isotopically Engineered Group-IV Color Centers in Diamond
A quantum register coupled to a spin-photon interface is a key component in
quantum communication and information processing. Group-IV color centers in
diamond (SiV, GeV, and SnV) are promising candidates for this application,
comprising an electronic spin with optical transitions coupled to a nuclear
spin as the quantum register. However, the creation of a quantum register for
these color centers with deterministic and strong coupling to the spin-photon
interface remains challenging. Here, we make first-principles predictions of
the hyperfine parameters of the group-IV color centers, which we verify
experimentally with a comprehensive comparison between the spectra of spin
active and spin neutral intrinsic dopant nuclei in single GeV and SnV emitters.
In line with the theoretical predictions, detailed spectroscopy on large sample
sizes reveals that hyperfine coupling causes a splitting of the optical
transition of SnV an order of magnitude larger than the optical linewidth and
provides a magnetic-field insensitive transition. This strong coupling provides
access to a new regime for quantum registers in diamond color centers, opening
avenues for novel spin-photon entanglement and quantum sensing schemes for
these well-studied emitters
Microwave-based quantum control and coherence protection of tin-vacancy spin qubits in a strain-tuned diamond membrane heterostructure
Robust spin-photon interfaces in solids are essential components in quantum
networking and sensing technologies. Ideally, these interfaces combine a
long-lived spin memory, coherent optical transitions, fast and high-fidelity
spin manipulation, and straightforward device integration and scaling. The
tin-vacancy center (SnV) in diamond is a promising spin-photon interface with
desirable optical and spin properties at 1.7 K. However, the SnV spin lacks
efficient microwave control and its spin coherence degrades with higher
temperature. In this work, we introduce a new platform that overcomes these
challenges - SnV centers in uniformly strained thin diamond membranes. The
controlled generation of crystal strain introduces orbital mixing that allows
microwave control of the spin state with 99.36(9) % gate fidelity and spin
coherence protection beyond a millisecond. Moreover, the presence of crystal
strain suppresses temperature dependent dephasing processes, leading to a
considerable improvement of the coherence time up to 223(10) s at 4 K, a
widely accessible temperature in common cryogenic systems. Critically, the
coherence of optical transitions is unaffected by the elevated temperature,
exhibiting nearly lifetime-limited optical linewidths. Combined with the
compatibility of diamond membranes with device integration, the demonstrated
platform is an ideal spin-photon interface for future quantum technologies
Confinement of long-lived interlayer excitons in WS 2 /WSe 2 heterostructures
Abstract: Interlayer excitons in layered materials constitute a novel platform to study many-body phenomena arising from long-range interactions between quantum particles. Long-lived excitons are required to achieve high particle densities, to mediate thermalisation, and to allow for spatially and temporally correlated phases. Additionally, the ability to confine them in periodic arrays is key to building a solid-state analogue to atoms in optical lattices. Here, we demonstrate interlayer excitons with lifetime approaching 0.2 ms in a layered-material heterostructure made from WS2 and WSe2 monolayers. We show that interlayer excitons can be localised in an array using a nano-patterned substrate. These confined excitons exhibit microsecond-lifetime, enhanced emission rate, and optical selection rules inherited from the host material. The combination of a permanent dipole, deterministic spatial confinement and long lifetime places interlayer excitons in a regime that satisfies one of the requirements for simulating quantum Ising models in optically resolvable lattices
Quantum Control of the Tin-Vacancy Spin Qubit in Diamond
Group-IV colour centres in diamond are a promising light-matter interface for quantum networking devices. We demonstrate multiaxis coherent control of the SnV spin-qubit via an all-optical stimulated Raman drive between the ground and excited states.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.QID/Hanson La
Quantum Control of the Tin-Vacancy Spin Qubit in Diamond
Group-IV color centers in diamond are a promising light-matter interface for quantum networking devices. The negatively charged tin-vacancy center (SnV) is particularly interesting, as its large spin-orbit coupling offers strong protection against phonon dephasing and robust cyclicity of its optical transitions toward spin-photon-entanglement schemes. Here, we demonstrate multiaxis coherent control of the SnV spin qubit via an all-optical stimulated Raman drive between the ground and excited states. We use coherent population trapping and optically driven electronic spin resonance to confirm coherent access to the qubit at 1.7 K and obtain spin Rabi oscillations at a rate of ω/2π=19.0(1) MHz. All-optical Ramsey interferometry reveals a spin dephasing time of T2∗=1.3(3) μs, and four-pulse dynamical decoupling already extends the spin-coherence time to T2=0.30(8) ms. Combined with transform-limited photons and integration into photonic nanostructures, our results make the SnV a competitive spin-photon building block for quantum networks.QID/Hanson La