16 research outputs found
Optically-Heralded Entanglement of Superconducting Systems in Quantum Networks
Networking superconducting quantum computers is a longstanding challenge in
quantum science. The typical approach has been to cascade transducers:
converting to optical frequencies at the transmitter and to microwave
frequencies at the receiver. However, the small microwave-optical coupling and
added noise have proven formidable obstacles. Instead, we propose optical
networking via heralding end-to-end entanglement with one detected photon and
teleportation. In contrast to cascaded direct transduction, our scheme absorbs
the low optical-microwave coupling efficiency into the heralding step, thus
breaking the rate-fidelity trade-off. Moreover, this technique unifies and
simplifies entanglement generation between superconducting devices and other
physical modalities in quantum networks
Airfoil Selection and Wingsail Design for an Autonomous Sailboat
Part of the Advances in Intelligent Systems and Computing book series (AISC, volume 1092)Ocean exploration and monitoring with autonomous platforms can provide researchers and decision makers with valuable data, trends and insights into the largest ecosystem on Earth. Regardless of the recognition of the importance of such platforms in this scenario, their design and development remains an open challenge. In particular, energy efficiency, control and robustness are major concerns with implications in terms of autonomy and sustainability. Wingsails allow autonomous boats to navigate with increased autonomy, due to lower power consumption, and greater robustness, due to simpler control. Within the scope of a project that addresses the design, development and deployment of a rigid wing autonomous sailboat to perform long term missions in the ocean, this paper summarises the general principles for airfoil selection and wingsail design in robotic sailing, and are given some insights on how these aspects influence the autonomous sailboat being developed by the authors.info:eu-repo/semantics/publishedVersio
Coherent control of a superconducting qubit using light
Quantum science and technology promise the realization of a powerful
computational resource that relies on a network of quantum processors connected
with low loss and low noise communication channels capable of distributing
entangled states [1,2]. While superconducting microwave qubits (3-8 GHz)
operating in cryogenic environments have emerged as promising candidates for
quantum processor nodes due to their strong Josephson nonlinearity and low loss
[3], the information between spatially separated processor nodes will likely be
carried at room temperature via telecommunication photons (200 THz) propagating
in low loss optical fibers. Transduction of quantum information [4-10] between
these disparate frequencies is therefore critical to leverage the advantages of
each platform by interfacing quantum resources. Here, we demonstrate coherent
optical control of a superconducting qubit. We achieve this by developing a
microwave-optical quantum transducer that operates with up to 1.18% conversion
efficiency (1.16% cooperativity) and demonstrate optically-driven Rabi
oscillations (2.27 MHz) in a superconducting qubit without impacting qubit
coherence times (800 ns). Finally, we discuss outlooks towards using the
transducer to network quantum processor nodes
Quantum interference of electromechanically stabilized emitters in nanophotonic devices
Photon-mediated coupling between distant matter qubits may enable secure
communication over long distances, the implementation of distributed quantum
computing schemes, and the exploration of new regimes of many-body quantum
dynamics. Nanophotonic devices coupled to solid-state quantum emitters
represent a promising approach towards realization of these goals, as they
combine strong light-matter interaction and high photon collection
efficiencies. However, the scalability of these approaches is limited by the
frequency mismatch between solid-state emitters and the instability of their
optical transitions. Here we present a nano-electromechanical platform for
stabilization and tuning of optical transitions of silicon-vacancy (SiV) color
centers in diamond nanophotonic devices by dynamically controlling their strain
environments. This strain-based tuning scheme has sufficient range and
bandwidth to alleviate the spectral mismatch between individual SiV centers.
Using strain, we ensure overlap between color center optical transitions and
observe an entangled superradiant state by measuring correlations of photons
collected from the diamond waveguide. This platform for tuning spectrally
stable color centers in nanophotonic waveguides and resonators constitutes an
important step towards a scalable quantum network
Strain engineering of the silicon-vacancy center in diamond
We control the electronic structure of the silicon-vacancy (SiV) color-center
in diamond by changing its static strain environment with a
nano-electro-mechanical system. This allows deterministic and local tuning of
SiV optical and spin transition frequencies over a wide range, an essential
step towards multi-qubit networks. In the process, we infer the strain
Hamiltonian of the SiV revealing large strain susceptibilities of order 1
PHz/strain for the electronic orbital states. We identify regimes where the
spin-orbit interaction results in a large strain suseptibility of order 100
THz/strain for spin transitions, and propose an experiment where the SiV spin
is strongly coupled to a nanomechanical resonator
Strain engineering of the silicon-vacancy center in diamond
We control the electronic structure of the silicon-vacancy (SiV) color-center in diamond by changing its static strain environment with a nano-electro-mechanical system. This allows deterministic and local tuning of SiV optical and spin transition frequencies over a wide range, an essential step towards multiqubit networks. In the process, we infer the strain Hamiltonian of the SiV revealing large strain susceptibilities of order 1 PHz/strain for the electronic orbital states. We identify regimes where the spin-orbit interaction results in a large strain susceptibility of order 100 THz/strain for spin transitions, and propose an experiment where the SiV spin is strongly coupled to a nanomechanical resonator
Error corrected spin-state readout in a nanodiamond
Quantum state readout is a key component of quantum technologies, including
applications in sensing, computation, and secure communication. Readout
fidelity can be enhanced by repeating readouts. However, the number of repeated
readouts is limited by measurement backaction, which changes the quantum state
that is measured. This detrimental effect can be overcome by storing the
quantum state in an ancilla qubit, chosen to be robust against measurement
backaction and to allow error correction. Here, we protect the electronic-spin
state of a diamond nitrogen-vacancy center from measurement backaction using a
robust multilevel 14N nuclear spin memory and perform repetitive readout, as
demonstrated in previous work on bulk diamond devices. We achieve additional
protection using error correction based on the quantum logic of coherent
feedback to reverse measurement backaction. The repetitive spin readout scheme
provides a 13-fold enhancement of readout fidelity over conventional readout
and the error correction a 2-fold improvement in the signal. These experiments
demonstrate full quantum control of a nitrogen vacancy center electronic spin
coupled to its host 14N nuclear spin inside a ~25 nm nanodiamond, creating a
sensitive and biologically compatible platform for nanoscale quantum sensing.
Our error-corrected repetitive readout scheme is particularly useful for
quadrupolar nuclear magnetic resonance imaging in the low magnetic field regime
where conventional repetitive readout suffers from strong measurement
backaction. More broadly, methods for correcting longitudinal (bit-flip) errors
described here could be used to improve quantum algorithms that require
nonvolatile local memory, such as correlation spectroscopy measurements for
high resolution sensing.Quantum Technology Hub NQIT EP/M013243/