[Show abstract][Hide abstract] ABSTRACT: Advances in single photon creation, transmission, and detection suggest that
sending quantum information over optical fibers may have losses low enough to
be correctable using a quantum error correcting code. Such error-corrected
communication is equivalent to a novel quantum repeater scheme, but crucial
questions regarding implementation and system requirements remain open. Here we
show that long range entangled bit generation with rates approaching $10^8$
ebits/s may be possible using a completely serialized protocol, in which
photons are generated, entangled, and error corrected via sequential, one-way
interactions with a minimal number of matter qubits. Provided loss and error
rates of the required elements are below the threshold for quantum error
correction, this scheme demonstrates improved performance over transmission of
single photons. We find improvement in ebit rates at large distances using this
serial protocol and various quantum error correcting codes.
[Show abstract][Hide abstract] ABSTRACT: Strong interactions between single spins and photons are essential for
quantum networks and distributed quantum computation. They provide the
necessary interface for entanglement distribution, non-destructive quantum
measurements, and strong photon-photon interactions. Achieving a spin-photon
interface in a solid-state device could enable compact chip-integrated quantum
circuits operating at gigahertz bandwidths. Many theoretical works have
suggested using nanophotonic structures to attain this high-speed interface.
These proposals exploit strong light-matter interactions to coherently switch a
photon with a single spin embedded in a nanoscale cavity or waveguide. However,
to date such an interface has not been experimentally realized using a
solid-state spin system. Here, we report an experimental demonstration of a
nanophotonic spin-photon quantum interface operating on picosecond timescales,
where a single solid-state spin controls the quantum state of a photon and a
single photon controls the state of the spin. We utilize an optical nano-cavity
strongly coupled to a charged quantum dot containing a single trapped spin. We
show that the spin-state strongly modulates the cavity reflection coefficient,
which conditionally flips the polarization state of a reflected photon. We also
demonstrate the complementary effect where a single photon applies a \pi\ phase
shift on one of the spin-states, thereby coherently rotating the spin. These
results demonstrate a spin-photon quantum phase gate that retains phase
coherence, an essential requirement for quantum information applications. Our
results open up a promising direction for solid-state implementations of
quantum networks and quantum computers operating at gigahertz bandwidths.
[Show abstract][Hide abstract] ABSTRACT: An emitter near a surface induces an image dipole that can modify the observed emission intensity and radiation pattern. These image-dipole effects are generally not taken into account in single-emitter tracking and super-resolved imaging applications. Here we show that the interference between an emitter and its image dipole induces a strong polarization anisotropy and a large spatial displacement of the observed emission pattern. We demonstrate these effects by tracking the emission of a single quantum dot along two orthogonal polarizations as it is deterministically positioned near a silver nanowire. The two orthogonally polarized diffraction spots can be displaced by up to 50 nm, which arises from a Young's interference effect between the quantum dot and its induced image dipole. We show that the observed spatially varying interference fringe provides a useful measure for correcting image-dipole-induced distortions. These results provide a pathway towards probing and correcting image-dipole effects in near-field imaging applications.
[Show abstract][Hide abstract] ABSTRACT: Nitrogen vacancy (NV) color centers in diamond enable local magnetic field sensing with high sensitivity by optical detection of electron spin resonance (ESR). The integration of this capability with microfluidic technology has a broad range of applications in chemical and biological sensing. We demonstrate a method to perform localized magnetometry in a microfluidic device with a 48 nm spatial precision. The device manipulates individual magnetic particles in three dimensions using a combination of flow control and magnetic actuation. We map out the local field distribution of the magnetic particle by manipulating it in the vicinity of a single NV center and optically detecting the induced Zeeman shift with a magnetic field sensitivity of 17.5 microTesla/Hz^1/2. Our results enable accurate nanoscale mapping of the magnetic field distribution of a broad range of target objects in a microfluidic device.
[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 experimentally demonstrate reversible strain-tuning of a quantum dot strongly coupled to a photonic crystal cavity. We observe a clear anti-crossing between the quantum dot and the cavity using the strain tuning technique.
Conference on Lasers and Electro-Optics, San Jose, California, United States; 06/2014
[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: 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: 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.
Proceedings of SPIE - The International Society for Optical Engineering 02/2014; 8970. DOI:10.1117/12.2042545 · 0.20 Impact Factor
[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: 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: 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: 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.