54 research outputs found
Storage and Retrieval of a Microwave Field in a Spin Ensemble
We report the storage and retrieval of a small microwave field from a
superconducting resonator into collective excitations of a spin ensemble. The
spins are nitrogen-vacancy centers in a diamond crystal. The storage time of
the order of 30 ns is limited by inhomogeneous broadening of the spin ensemble.Comment: 4 pages + supplementary material. Submitted to PR
Entanglement of a Mesoscopic Field with an Atom induced by Photon Graininess in a Cavity
We observe that a mesoscopic field made of several tens of microwave photons
exhibits quantum features when interacting with a single Rydberg atom in a
high-Q cavity. The field is split into two components whose phases differ by an
angle inversely proportional to the square root of the average photon number.
The field and the atomic dipole are phase-entangled. These manifestations of
photon graininess vanish at the classical limit. This experiment opens the way
to studies of large Schrodinger cat states at the quantum-classical boundary
Tunable cavity coupling of the zero phonon line of a nitrogen-vacancy defect in diamond
We demonstrate the tunable enhancement of the zero phonon line of a single
nitrogen-vacancy color center in diamond at cryogenic temperature. An open
cavity fabricated using focused ion beam milling provides mode volumes as small
as 1.24 m. In-situ tuning of the cavity resonance is achieved with
piezoelectric actuators. At optimal coupling of the full open cavity the signal
from individual zero phonon line transitions is enhanced by about a factor of
10 and the overall emission rate of the NV center is increased by 40%
compared with that measured from the same center in the absence of cavity field
confinement. This result is important for the realization of efficient
spin-photon interfaces and scalable quantum computing using optically
addressable solid state spin qubits.Comment: 11 pages Main Article + 4 pages Supplementary Info Typos fixed from
v
Cavity-Enhanced Two-Photon Interference using Remote Quantum Dot Sources
Quantum dots in cavities have been shown to be very bright sources of
indistinguishable single photons. Yet the quantum interference between two
bright quantum dot sources, a critical step for photon based quantum
computation, has never been investigated. Here we report on such a measurement,
taking advantage of a deterministic fabrication of the devices. We show that
cavity quantum electrodynamics can efficiently improve the quantum interference
between remote quantum dot sources: poorly indistinguishable photons can still
interfere with good contrast with high quality photons emitted by a source in
the strong Purcell regime. Our measurements and calculations show that cavity
quantum electrodynamics is a powerful tool for interconnecting several devices.Comment: 5 pages, 4 figures (Supp. Mat. attached
Strong Coupling of a Spin Ensemble to a Superconducting Resonator
We report the realization of a quantum circuit in which an ensemble of
electronic spins is coupled to a frequency tunable superconducting resonator.
The spins are Nitrogen-Vacancy centers in a diamond crystal. The achievement of
strong coupling is manifested by the appearance of a vacuum Rabi splitting in
the transmission spectrum of the resonator when its frequency is tuned through
the NV center electron spin resonance.Comment: 4 pages, 3 figure
Electron spin resonance detected by a superconducting qubit
A new method for detecting the magnetic resonance of electronic spins at low
temperature is demonstrated. It consists in measuring the signal emitted by the
spins with a superconducting qubit that acts as a single-microwave-photon
detector, resulting in an enhanced sensitivity. We implement this new type of
electron-spin resonance spectroscopy using a hybrid quantum circuit in which a
transmon qubit is coupled to a spin ensemble consisting of NV centers in
diamond. With this setup we measure the NV center absorption spectrum at 30mK
at an excitation level of \thicksim15\,\mu_{B} out of an ensemble of 10^{11}
spins.Comment: 6 pages, 4 figures, submitted to PR
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