[Show abstract][Hide abstract] ABSTRACT: When an atom strongly couples to a cavity, it can undergo coherent vacuum
Rabi oscillations. Controlling these oscillatory dynamics quickly relative to
the vacuum Rabi frequency enables remarkable capabilities such as Fock state
generation and deterministic synthesis of quantum states of light, as
demonstrated using microwave frequency devices. At optical frequencies,
however, dynamical control of single-atom vacuum Rabi oscillations remains
challenging. Here, we demonstrate coherent transfer of optical frequency
excitation between a single quantum dot and a cavity by controlling vacuum Rabi
oscillations. We utilize a photonic molecule to simultaneously attain strong
coupling and a cavity-enhanced AC Stark shift. The Stark shift modulates the
detuning between the two systems on picosecond timescales, faster than the
vacuum Rabi frequency. We demonstrate the ability to add and remove excitation
from the cavity, and perform coherent control of light-matter states. These
results enable ultra-fast control of atom-cavity interactions in a nanophotonic
[Show abstract][Hide abstract] ABSTRACT: Nitrogen vacancy (NV) color centers in diamond have emerged as highly
versatile optical emitters that exhibit room temperature spin properties. These
characteristics make NV centers ideal for magnetometry which plays an important
role in a broad range of chemical and biological sensing applications. The
integration of NV magnetometers with microfluidic systems could enable the
study of isolated chemical and biological samples in a fluid environment with
high spatial resolution. Here we demonstrate a method to perform localized
magnetometry with nanometer spatial precision using a single NV center in a
microfluidic device. We manipulate a magnetic particle within a liquid
environment using a combination of planar flow control and vertical magnetic
actuation to achieve 3-dimensional manipulation. A diamond nanocrystal
containing a single NV center is deposited in the microfluidic channels and
acts as a local magnetic field probe. We map out the magnetic field
distribution of the magnetic particle by varying its position relative to the
diamond nanocrystal and performing optically resolved electron spin resonance
(ESR) measurements. We control the magnetic particle position with a 48 nm
precision and attain a magnetic field sensitivity of 17.5 microTesla/Hz^1/2.
These results open up the possibility for studying local magnetic properties of
biological and chemical systems with high sensitivity in an integrated
[Show abstract][Hide abstract] ABSTRACT: We demonstrate spontaneous emission enhancement (by an average factor of 4.6) and saturable absorption of cadmium selenide colloidal quantum dots coupled to a nanobeam photonic crystal cavity, at room temperature.
[Show abstract][Hide abstract] ABSTRACT: By combining magnetic nanoparticle 3D positioning system and NV ESR measurements in micro-fluid device, we demonstrate sensing of magnetic fringe field of a magnetic bead repeatedly displaced and mapping field profile of the magnetic dipole.
[Show abstract][Hide abstract] ABSTRACT: We demonstrate a method to control the coupling interaction in a coupled-cavity photonic crystal molecule by using a local and reversible photochromic tuning technique. This method is promising for development of integrated photonic devices with large number of cavities.
[Show abstract][Hide abstract] ABSTRACT: Despite the rapid growth of microfabrication technologies over the past decades, many desirable microstructures remain difficult or even impossible to create, especially when the structures are composed of multiple components that feature different materials that must be arranged in a highly specific, 3-D pattern. We have developed aqueous photoresists that can be used in combination with different techniques for nanomanipulation to create such structures. Multiphoton absorption polymerization can be used to create unsupported polymeric microstructures that can be nanomanipulated to place them in any desired position and orientation. Nanomanipulation techniques can also be used to place micro- or nanoscale components in desired locations in three dimensions, after which they can be immobilized photochemically. This toolbox of techniques offers the capability of creating a broad range of new structures and devices featuring polymeric, inorganic, metallic and biomolecular components.
[Show abstract][Hide abstract] ABSTRACT: We propose a method to overcome Auger recombination in nanocrystal quantum dot lasers using cavity-enhanced spontaneous emission. We derive a numerical model for a laser composed of nanocrystal quantum dots coupled to optical nanocavities with small mode-volume. Using this model, we demonstrate that spontaneous emission enhancement of the biexciton transition lowers the lasing threshold by reducing the effect of Auger recombination. We analyze a photonic crystal nanobeam cavity laser as a realistic device structure that implements the proposed approach.
[Show abstract][Hide abstract] ABSTRACT: We demonstrate spontaneous emission rate enhancement and saturable absorption of cadmium selenide colloidal quantum dots coupled to a nanobeam photonic crystal cavity. We perform time-resolved lifetime measurements and observe an average enhancement of 4.6 for the spontaneous emission rate of quantum dots located at the cavity as compared to those located on an unpatterned surface. We also demonstrate that the cavity linewidth narrows with increasing pump intensity due to quantum dot saturable absorption.
[Show abstract][Hide abstract] ABSTRACT: We experimentally demonstrate that the Mollow triplet sidebands of a quantum
dot strongly coupled to a cavity exhibit anomalous power induced broadening and
enhanced emission when one sideband is tuned over the cavity frequency. We
observe a nonlinear increase of the sideband linewidth with excitation power
when the Rabi frequency exceeds the detuning between the quantum dot and the
cavity, consistent with a recent theoretical model that accounts for acoustic
phonon-induced processes between the exciton and the cavity. In addition, the
sideband tuned to the cavity shows strong resonant emission enhancement.
[Show abstract][Hide abstract] ABSTRACT: Synthetic nanostructures, such as nanoparticles and nanowires, can serve as modular building blocks for integrated nanoscale systems. We demonstrate a microfluidic approach for positioning, orienting, and assembling such nanostructures into nanoassemblies. We use flow control combined with a crosslinking photoresist to position and immobilize nanostructures in desired positions and orientations. Immobilized nanostructures can serve as pivots, barriers, and guides for precise placement of subsequent nanostructures.
[Show abstract][Hide abstract] ABSTRACT: Individual colloidal quantum dots are manipulated in a microfluidic device and used as near-field optical probes for visualizing the plasmonic mode of a silver nanowire.
[Show abstract][Hide abstract] ABSTRACT: Effects beyond cw-Stark shift is investigated in a strongly coupled quantum dot-cavity system using the full quantum master equations, when the dot is dynamically detuned by an off-resonant laser pulse.
[Show abstract][Hide abstract] ABSTRACT: We demonstrate reversible strain-tuning of a quantum dot strongly coupled to
a photonic crystal cavity. We observe an average redshift of 0.45 nm for
quantum dots located inside the cavity membrane, achieved with an electric
field of 15 kV/cm applied to a piezo-electric actuator. Using this technique,
we demonstrate the ability to tune a quantum dot into resonance with a photonic
crystal cavity in the strong coupling regime, resulting in a clear
anti-crossing. The bare cavity resonance is less sensitive to strain than the
quantum dot and shifts by only 0.078 nm at the maximum applied electric field.
[Show abstract][Hide abstract] ABSTRACT: Integrated nanophotonic devices create strong light-matter interactions
that are important for the development of solid-state quantum networks,
distributed quantum computers and ultralow-power optoelectronics. A key
component for many of these applications is the photonic quantum logic
gate, where the quantum state of a solid-state quantum bit (qubit)
conditionally controls the state of a photonic qubit. These gates are
crucial for the development of robust quantum networks, non-destructive
quantum measurements and strong photon-photon interactions. Here, we
experimentally realize a quantum logic gate between an optical photon
and a solid-state qubit. The qubit is composed of a quantum dot strongly
coupled to a nanocavity, which acts as a coherently controllable qubit
system that conditionally flips the polarization of a photon on
picosecond timescales, implementing a controlled-NOT gate. Our results
represent an important step towards solid-state quantum networks and
provide a versatile approach for probing quantum dot-photon interactions
on ultrafast timescales.
[Show abstract][Hide abstract] ABSTRACT: We present a method to control the resonant coupling interaction in a coupled-cavity photonic crystal molecule by using a local and reversible photochromic tuning technique. We demonstrate the ability to tune both a two-cavity and a three-cavity photonic crystal molecule through the resonance condition by selectively tuning the individual cavities. Using this technique, we can quantitatively determine important parameters of the coupled-cavity system such as the photon tunneling rate. This method can be scaled to photonic crystal molecules with larger numbers of cavities, which provides a versatile method for studying strong interactions in coupled resonator arrays.
[Show abstract][Hide abstract] ABSTRACT: Strong interactions between matter quantum bits (qubits) and photons
play an essential role in quantum information. Quantum dots (QDs)
provide a promising implementation of a matter qubit that can be
strongly coupled to optical nanocavities, providing a direct
light-matter interface. We use this light-matter interface to
demonstrate a picosecond timescale controlled NOT logic gate between a
QD and a photon, which is a fundamental building block for complex
quantum logic. Coherent control of the QD qubit state by optical pulses
results in a modification of cavity reflectivity, enabling a conditional
bit-flip on the polarization state of a photon incident on the cavity.
[Show abstract][Hide abstract] ABSTRACT: Understanding and controlling the interactions between single quantum
emitters and plasmonic nanostructures is important for a wide variety of
applications in quantum optics and nanophotonics. Metal nanostructures
provide subwavelength confinement of electromagnetic fields in the form
of surface plasmon polaritons, which can enhance optical nonlinearities
for improved light-matter interactions. In this talk we will present
recent results on nano-manipulation of single colloidal quantum dots
(QDs) for deterministic probing of light-matter interactions in
plasmonic nanostructures. Single QDs are manipulated using a combination
of microfluidics and engineered fluid chemistry. We achieve
deterministic positioning with 50 nm accuracy and demonstrate probing of
the surface plasmon mode of a silver nanowire. Spatially variant
interactions are quantified by measuring the coupling rate of the QD
into the wire mode as well as changes to the QD emission lifetime. The
resulting interactions are resolved with nanoscale resolution and reveal
features such as the evanescent field decay away from the wire surface
and interference along the wire length.
[Show abstract][Hide abstract] ABSTRACT: Single semiconductor quantum-dots (QDs) strongly coupled to photonic
crystal cavities are a strong candidate for single photon generation,
ultra-fast all optical switching and quantum information processing.
Recent experiments on coupled-cavity quantum dot systems show possible
manipulation of emission wavelength of the dot through optical Stark
effect. Interesting dynamical features arise when the Stark pulse
duration is comparable to QD-cavity interaction time. Here, we present a
theoretical treatment of these dynamical effects and investigate
dynamical emission spectrum, energy transfer and single photon
generation. We study these effects through numerical solution of the
full master equation. We demonstrate that dynamic Stark effects can be
used to generate ultra-fast indistinguishable single photons using rapid
Stark tuning of the quantum dot. The theoretical limit for the speed is
shown to be faster than adiabatic rapid passage technique used for
microwave photon generation in circuit QED. A systematic study of role
of device parameters such as pulse-shape, dot-cavity coupling and
incoherent losses on the efficiency and speed of single photon
generation is also presented for possible experimental realization.
[Show abstract][Hide abstract] ABSTRACT: The interaction of semiconductor quantum dots (QD) with photonic crystal
resonator systems provides a highly integrated, solid-state platform for
studies in ultra-low energy nonlinear optics and quantum optical
phenomena. Here, we present a method to tune a semiconductor quantum dot
(QD) all-optically into resonance with a cavity mode using the
non-resonant optical Stark effect. We use a system comprised of two
evanescently coupled photonic crystal cavities containing a single QD in
one of the cavities. One mode of the coupled cavity system is used to
generate a cavity-enhanced optical Stark shift, enabling the QD to be
resonantly tuned to the other cavity mode. We show that the optical
tuning of the QD results in a large radiative enhancement of the QD
photon emission via the Purcell effect. We will further discuss dynamic
experiments in the system using a Stark laser that has a time-duration
on the order of the system decay rates. We will show that under this
scenario, the cavity-QD spectrum provides a rich array of information on
the system dynamics. The experiments are promising for a variety of
applications in highly-efficient single photon generation, cavity
quantum electrodynamics, ultra-fast optical switching, and classical and
quantum information processing.
[Show abstract][Hide abstract] ABSTRACT: Strongly coupled photonic crystal (PhC) resonator systems provide a
promising platform for studying cavity quantum electrodynamics (QED)
using semiconductor quantum dots (QDs). These device structures enable
important applications such as photon blockade, quantum simulation,
quantum-optical Josephson interferometer, and quantum phase transition
of light. Many of these applications require the ability to accurately
tune the resonant frequencies of individual cavities in the array, which
provides a method to control their coupling interactions. This tuning
method must be sufficiently local to address individual cavities spaced
by less than 1 micron spatial separation. Here, we present a method for
controlling the coupling interaction of photonic crystal cavity arrays
by using a local and reversible photochromic tuning technique. By
locally altering the refractive index of the photochromic material
all-optically, the coupling interaction between two cavity modes could
be modified over a tuning range as large as 700 GHz. By using this
technique, we demonstrate the ability to couple photonic crystal
cavities with a normal mode splitting of only 31.50 GHz. We further
demonstrate that this tuning method can be extended to control the
coupling interaction in larger cavity arrays.