35 research outputs found
Spatially Adiabatic Frequency Conversion in Optoelectromechanical Arrays
Faithful conversion of quantum signals between microwave and optical
frequency domains is crucial for building quantum networks based on
superconducting circuits. Optoelectromechanical systems, in which microwave and
optical cavity modes are coupled to a common mechanical oscillator, are a
promising route towards this goal. In these systems, efficient, low-noise
conversion is possible using a mechanically dark mode of the fields but the
conversion bandwidth is limited to a fraction of the cavity linewidth. Here, we
show that an array of optoelectromechanical transducers can overcome this
limitation and reach a bandwidth that is larger than the cavity linewidth. The
coupling rates are varied in space throughout the array so that the
mechanically dark mode of the propagating fields adiabatically changes from
microwave to optical or vice versa. This strategy also leads to significantly
reduced thermal noise with the collective optomechanical cooperativity being
the relevant figure of merit. Finally, we demonstrate that, quite surprisingly,
the bandwidth enhancement per transducer element is largest for small arrays;
this feature makes our scheme particularly attractive for state-of-the-art
experimental setups.Comment: 18 pages, 10 figures (including Supplemental Material
Interfacing single photons and single quantum dots with photonic nanostructures
Photonic nanostructures provide means of tailoring the interaction between
light and matter and the past decade has witnessed a tremendous experimental
and theoretical progress in this subject. In particular, the combination with
semiconductor quantum dots has proven successful. This manuscript reviews
quantum optics with excitons in single quantum dots embedded in photonic
nanostructures. The ability to engineer the light-matter interaction strength
in integrated photonic nanostructures enables a range of fundamental
quantum-electrodynamics experiments on, e.g., spontaneous-emission control,
modified Lamb shifts, and enhanced dipole-dipole interaction. Furthermore,
highly efficient single-photon sources and giant photon nonlinearities may be
implemented with immediate applications for photonic quantum-information
processing. The review summarizes the general theoretical framework of photon
emission including the role of dephasing processes, and applies it to photonic
nanostructures of current interest, such as photonic-crystal cavities and
waveguides, dielectric nanowires, and plasmonic waveguides. The introduced
concepts are generally applicable in quantum nanophotonics and apply to a large
extent also to other quantum emitters, such as molecules, nitrogen vacancy
ceters, or atoms. Finally, the progress and future prospects of applications in
quantum-information processing are considered.Comment: Updated version resubmitted to Reviews of Modern Physic
Quantum networks with chiral light--matter interaction in waveguides
We propose a scalable architecture for a quantum network based on a simple
on-chip photonic circuit that performs loss-tolerant two-qubit measurements.
The circuit consists of two quantum emitters positioned in the arms of an
on-chip Mach-Zehnder interferometer composed of waveguides with chiral
light--matter interfaces. The efficient chiral light--matter interaction allows
the emitters to perform high-fidelity intranode two-qubit parity measurements
within a single chip, and to emit photons to generate internode entanglement,
without any need for reconfiguration. We show that by connecting multiple
circuits of this kind into a quantum network, it is possible to perform
universal quantum computation with heralded two-qubit gate fidelities achievable in state-of-the-art quantum dot systems.Comment: 5 pages plus supplementary materia
Numerical modelling of the coupling efficiency of single quantum emitters in photonic-crystal waveguides
Planar photonic nanostructures have recently attracted a great deal of
attention for quantum optics applications. In this article, we carry out full
3D numerical simulations to fully account for all radiation channels and
thereby quantify the coupling efficiency of a quantum emitter embedded in a
photonic-crystal waveguide. We utilize mixed boundary conditions by combining
active Dirichlet boundary conditions for the guided mode and perfectly-matched
layers for the radiation modes. In this way, the leakage from the quantum
emitter to the surrounding environment can be determined and the spectral and
spatial dependence of the coupling to the radiation modes can be quantified.
The spatial maps of the coupling efficiency, the -factor, reveal that
even for moderately slow light, near-unity is achievable that is
remarkably robust to the position of the emitter in the waveguide. Our results
show that photonic-crystal waveguides constitute a suitable platform to achieve
deterministic interfacing of a single photon and a single quantum emitter,
which has a range of applications for photonic quantum technology
Dynamics of many-body photon bound states in chiral waveguide QED
We theoretically study the few- and many-body dynamics of photons in chiral
waveguides. In particular, we examine pulse propagation through a system of
two-level systems chirally coupled to a waveguide. We show that the system
supports correlated multi-photon bound states, which have a well-defined photon
number and propagate through the system with a group delay scaling as
. This has the interesting consequence that, during propagation, an
incident coherent state pulse breaks up into different bound state components
that can become spatially separated at the output in a sufficiently long
system. For sufficiently many photons and sufficiently short systems, we show
that linear combinations of -body bound states recover the well-known
phenomenon of mean-field solitons in self-induced transparency. For longer
systems, however, the solitons break apart through quantum correlated dynamics.
Our work thus covers the entire spectrum from few-photon quantum propagation,
to genuine quantum many-body (atom and photon) phenomena, and ultimately the
quantum-to-classical transition. Finally, we demonstrate that the bound states
can undergo elastic scattering with additional photons. Together, our results
demonstrate that photon bound states are truly distinct physical objects
emerging from the most elementary light-matter interaction between photons and
two-level emitters. Our work opens the door to studying quantum many-body
physics and soliton physics with photons in chiral waveguide QED.Comment: Updated with new results. 14 pages plus supplementary materia
Engineering chiral light-matter interaction in photonic crystal waveguides with slow light
We design photonic crystal waveguides with efficient chiral light--matter
interfaces that can be integrated with solid-state quantum emitters. By using
glide-plane-symmetric waveguides, we show that chiral light-matter interaction
can exist even in the presence of slow light with slow-down factors of up to
and therefore the light--matter interaction exhibits both strong Purcell
enhancement and chirality. This allows for near-unity directional
-factors for a range of emitter positions and frequencies. Additionally,
we design an efficient mode adapter to couple light from a standard nanobeam
waveguide to the glide-plane symmetric photonic crystal waveguide. Our work
sets the stage for performing future experiments on a solid-state platform
Dynamics of Many-Body Photon Bound States in Chiral Waveguide QED
We theoretically study the few- and many-body dynamics of photons in chiral waveguides. In particular, we examine pulse propagation through an ensemble of N two-level systems chirally coupled to a waveguide. We show that the system supports correlated multiphoton bound states, which have a well-defined photon number n and propagate through the system with a group delay scaling as 1/n2. This has the interesting consequence that, during propagation, an incident coherent-state pulse breaks up into different bound-state components that can become spatially separated at the output in a sufficiently long system. For sufficiently many photons and sufficiently short systems, we show that linear combinations of n-body bound states recover the well-known phenomenon of mean-field solitons in self-induced transparency. Our work thus covers the entire spectrum from few-photon quantum propagation, to genuine quantum many-body (atom and photon) phenomena, and ultimately the quantum-to-classical transition. Finally, we demonstrate that the bound states can undergo elastic scattering with additional photons. Together, our results demonstrate that photon bound states are truly distinct physical objects emerging from the most elementary light-matter interaction between photons and two-level emitters. Our work opens the door to studying quantum many-body physics and soliton physics with photons in chiral waveguide QED. © 2020 authors
Supermodes of Hexagonal Lattice Waveguide Arrays
We present a semi-analytical formulation for calculating the supermodes and
corresponding Bloch factors of light in hexagonal lattice photonic crystal
waveguide arrays. We then use this formulation to easily calculate dispersion
curves and predict propagation in systems too large to calculate using standard
numerical methods.Comment: Accepted by J. Opt. Soc. Am. B, DocID:160522.
http://www.opticsinfobase.org/abstract.cfm?msid=16052
Unraveling two-photon entanglement via the squeezing spectrum of light traveling through nanofiber-coupled atoms
We observe that a weak guided light field transmitted through an ensemble of
atoms coupled to an optical nanofiber exhibits quadrature squeezing. From the
measured squeezing spectrum we gain direct access to the phase and amplitude of
the energy-time entangled part of the two-photon wavefunction which arises from
the strongly correlated transport of photons through the ensemble. For small
atomic ensembles we observe a spectrum close to the lineshape of the atomic
transition, while sidebands are observed for sufficiently large ensembles, in
agreement with our theoretical predictions. Furthermore, we vary the detuning
of the probe light with respect to the atomic resonance and infer the phase of
the entangled two-photon wavefunction. From the amplitude and the phase of the
spectrum, we reconstruct the real- and imaginary part of the time-domain
wavefunction. Our characterization of the entangled two-photon component
constitutes a diagnostic tool for quantum optics devices