46 research outputs found
Transmon in a semi-infinite high-impedance transmission line -- appearance of cavity modes and Rabi oscillations
In this letter, we investigate the dynamics of a single superconducting
artificial atom capacitively coupled to a transmission line with a
characteristic impedance comparable or larger than the quantum resistance. In
this regime, microwaves are reflected from the atom also at frequencies far
from the atom's transition frequency. Adding a single mirror in the
transmission line then creates cavity modes between the atom and the mirror.
Investigating the spontaneous emission from the atom, we then find Rabi
oscillations, where the energy oscillates between the atom and one of the
cavity modes
Semiclassical analysis of dark-state transient dynamics in waveguide circuit QED
The interaction between superconducting qubits and one-dimensional microwave transmission lines has been studied experimentally and theoretically in the past two decades. In this work, we investigate the spontaneous emission of an initially excited artificial atom which is capacitively coupled to a semi-infinite transmission line, shorted at one end. This configuration can be viewed as an atom in front of a mirror. The distance between the atom and the mirror introduces a time delay in the system, which we take into account fully. When the delay time equals an integer number of atom oscillation periods, the atom converges into a dark state after an initial decay period. The dark state is an effect of destructive interference between the reflected part of the field and the part directly emitted by the atom. Based on circuit quantization, we derive linearized equations of motion for the system and use these for a semiclassical analysis of the transient dynamics. We also make a rigorous connection to the quantum optics system-reservoir approach and compare these two methods to describe the dynamics. We find that both approaches are equivalent for transmission lines with a low characteristic impedance, while they differ when this impedance is higher than the typical impedance of the superconducting artificial atom
Phonon-mediated dark to bright plasmon conversion
The optical response of a matter excitation embedded in nanophotonic devices
is commonly described by the Drude-Lorentz model. Here, we demonstrate that
this widely used approach fails in the case where quantum-confined plasmons of
a two-dimensional electron gas interact strongly with optical phonons. We
propose a new quantum model which contains the semiclassical Drude-Lorentz one
for simple electronic potentials, but predicts very different results in
symmetry-broken potentials. We unveil a new mechanism for the oscillator
strength transfer between bright phonon-polariton and dark plasmon modes,
enabling thus new quantum degrees of freedom for designing the optical response
of nanostructures
Comparative study of plasmonic antennas for strong coupling and quantum nonlinearities with single emitters
Realizing strong coupling between a single quantum emitter (QE) and an
optical cavity is of crucial importance in the context of various quantum
optical applications. While Rabi splitting of single quantum emitters coupled
to high-Q diffraction limited cavities have been reported in numerous
configurations, attaining single emitter Rabi splitting with a plasmonic
nanostructure is still elusive. Here, we establish the analytical condition for
strong coupling between a single QE and a plasmonic nanocavity and apply it to
study various plasmonic arrangements that were shown to enable Rabi splitting.
We investigate numerically the optical response and the resulting Rabi
splitting in metallic nanostructures such as bow-tie nanoantennas, nanosphere
dimers and nanospheres on a surface and find the optimal geometries for
emergence of the strong coupling regime with single QEs. We also provide a
master equation approach to show the saturation of a single QE in the gap of a
silver bow-tie nanoantenna. Our results will be useful for implementation of
realistic quantum plasmonic nanosystems involving single QEs.Comment: 9 pages, 7 figure
Unconventional saturation effects at intermediate drive in a lossy cavity coupled to few emitters
Recent technological advancements have enabled strong light-matter
interaction in highly dissipative cavity-emitter systems. However, in these
systems, which are well described by the Tavis-Cummings model, the considerable
loss rates render the realization of many desirable nonlinear effects, such as
saturation and photon blockade, problematic. Here we present another effect
occurring within the Tavis-Cummings model: a nonlinear response of the cavity
for resonant external driving of intermediate strength, which makes use of
large cavity dissipation rates. In this regime, -photon processes
dominate when the cavity couples to emitters. We explore and characterize
this effect in detail, and provide a picture of how the effect occurs due to
destructive interference between the emitter ensemble and the external drive.
We find that a central condition for the observed effect is large
cooperativity, i.e., the product of the cavity and emitter decay rates is much
smaller than the collective cavity-emitter interaction strength squared.
Importantly, this condition does not require strong coupling. We also find an
analytical expression for the critical drive strength at which the effect
appears. Our results have potential for quantum state engineering, e.g., photon
filtering, and could be used for the characterization of cavity-emitter systems
where the number of emitters is unknown. In particular, our results open the
way for investigations of unique quantum-optics applications in a variety of
platforms that neither require high-quality cavities nor strong coupling.Comment: 27 pages, 13 figures. New material including analytical calculations
and discussions about approximation
Strong coupling out of the blue: an interplay of quantum emitter hybridization with plasmonic dark and bright modes
Strong coupling between a single quantum emitter and an electromagnetic mode
is one of the key effects in quantum optics. In the cavity QED approach to
plasmonics, strongly coupled systems are usually understood as
single-transition emitters resonantly coupled to a single radiative plasmonic
mode. However, plasmonic cavities also support non-radiative (or "dark") modes,
which offer much higher coupling strengths. On the other hand, realistic
quantum emitters often support multiple electronic transitions of various
symmetry, which could overlap with higher order plasmonic transitions -- in the
blue or ultraviolet part of the spectrum. Here, we show that vacuum Rabi
splitting with a single emitter can be achieved by leveraging dark modes of a
plasmonic nanocavity. Specifically, we show that a significantly detuned
electronic transition can be hybridized with a dark plasmon pseudomode,
resulting in the vacuum Rabi splitting of the bright dipolar plasmon mode. We
develop a simple model illustrating the modification of the system response in
the "dark" strong coupling regime and demonstrate single photon non-linearity.
These results may find important implications in the emerging field of room
temperature quantum plasmonics
Upper bounds on collective light-matter coupling strength with plasmonic meta-atoms
Ultrastrong coupling between optical and material excitations is a distinct
regime of electromagnetic interaction that enables a variety of intriguing
physical phenomena. Traditional ways to ultrastrong light-matter coupling
involve the use of some sorts of quantum emitters, such as organic dyes,
quantum wells, superconducting artificial atoms, or transitions of
two-dimensional electron gases. Often, reaching the ultrastrong coupling domain
requires special conditions, including high vacuum, strong magnetic fields, and
extremely low temperatures. Recent report indicate that a high degree of
light-matter coupling can be attained at ambient conditions with plasmonic
meta-atoms -- artificial metallic nanostructures that replace quantum emitters.
Yet, the fundamental limits on the coupling strength imposed on such systems
have not been identified. Here, using a Hamiltonian approach we theoretically
analyze the formation of polaritonic states and examine the upper limits of the
collective plasmon-photon coupling strength in a number of dense assemblies of
plasmonic meta-atoms. Starting off with spheres, we identify the universal
upper bounds on the normalized collective coupling strength
between ensembles of plasmonic meta-atoms and free-space photons. Next, we
examine spheroidal metallic meta-atoms and show that a strongly elongated
meta-atom is the optimal geometry for attaining the highest value of the
collective coupling strength in the array of meta-atoms. The results could be
valuable for the field of polaritonics studies, quantum technology, and
modifying material properties
Ultrastrong coupling between nanoparticle plasmons and cavity photons at ambient conditions
Ultrastrong coupling is a distinct regime of electromagnetic interaction that
enables a rich variety of intriguing physical phenomena. Traditionally, this
regime has been reached by coupling intersubband transitions of multiple
quantum wells, superconducting artificial atoms, or two-dimensional electron
gases to microcavity resonators. However, employing these platforms requires
demanding experimental conditions such as cryogenic temperatures, strong
magnetic fields, and high vacuum. Here, we use plasmonic nanorods array
positioned at the antinode of the resonant optical Fabry-P\'erot microcavity to
reach the ultrastrong coupling (USC) regime at ambient conditions and without
the use of magnetic fields. From optical measurements we extract the value of
the interaction strength over the transition energy as high as g/{\omega}~0.55,
deep in the USC regime, while the nanorods array occupies only ~4% of the
cavity volume. Moreover, by comparing the resonant energies of the coupled and
uncoupled systems, we indirectly observe up to ~10% modification of the
ground-state energy, which is a hallmark of USC. Our results suggest that
plasmon-microcavity polaritons are a promising new platform for
room-temperature USC realizations in the optical and infrared range.Comment: 4 figure
Satellite sensor requirements for monitoring essential biodiversity variables of coastal ecosystems
© The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Ecological Applications 28 (2018): 749-760, doi: 10.1002/eap.1682.The biodiversity and high productivity of coastal terrestrial and aquatic habitats are the foundation for important benefits to human societies around the world. These globally distributed habitats need frequent and broad systematic assessments, but field surveys only cover a small fraction of these areas. Satellite‐based sensors can repeatedly record the visible and near‐infrared reflectance spectra that contain the absorption, scattering, and fluorescence signatures of functional phytoplankton groups, colored dissolved matter, and particulate matter near the surface ocean, and of biologically structured habitats (floating and emergent vegetation, benthic habitats like coral, seagrass, and algae). These measures can be incorporated into Essential Biodiversity Variables (EBVs), including the distribution, abundance, and traits of groups of species populations, and used to evaluate habitat fragmentation. However, current and planned satellites are not designed to observe the EBVs that change rapidly with extreme tides, salinity, temperatures, storms, pollution, or physical habitat destruction over scales relevant to human activity. Making these observations requires a new generation of satellite sensors able to sample with these combined characteristics: (1) spatial resolution on the order of 30 to 100‐m pixels or smaller; (2) spectral resolution on the order of 5 nm in the visible and 10 nm in the short‐wave infrared spectrum (or at least two or more bands at 1,030, 1,240, 1,630, 2,125, and/or 2,260 nm) for atmospheric correction and aquatic and vegetation assessments; (3) radiometric quality with signal to noise ratios (SNR) above 800 (relative to signal levels typical of the open ocean), 14‐bit digitization, absolute radiometric calibration <2%, relative calibration of 0.2%, polarization sensitivity <1%, high radiometric stability and linearity, and operations designed to minimize sunglint; and (4) temporal resolution of hours to days. We refer to these combined specifications as H4 imaging. Enabling H4 imaging is vital for the conservation and management of global biodiversity and ecosystem services, including food provisioning and water security. An agile satellite in a 3‐d repeat low‐Earth orbit could sample 30‐km swath images of several hundred coastal habitats daily. Nine H4 satellites would provide weekly coverage of global coastal zones. Such satellite constellations are now feasible and are used in various applications.National Center for Ecological Analysis and Synthesis (NCEAS);
National Aeronautics and Space Administration (NASA) Grant Numbers: NNX16AQ34G, NNX14AR62A;
National Ocean Partnership Program;
NOAA US Integrated Ocean Observing System/IOOS Program Office;
Bureau of Ocean and Energy Management Ecosystem Studies program (BOEM) Grant Number: MC15AC0000