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Quantum Optics Including Noise Reduction, Trapp... ((FREE))

The extension of the above integrated photonics technology, including detectors and waveguides to optical cross-connect switches, to the visible and blue portions of the spectrum where atomic ions respond will be highly valuable to the trapped ion quantum optical network. Alternatively, noiseless photonic conversion technology from visible/blue to infrared and telecom bands will have an important role, especially for long-distance quantum communication network applications.

Quantum Optics Including Noise Reduction, Trapp...

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A central challenge in quantum computing remains the creation of low-noise qubits that can be scaled to sufficiently high numbers for useful computation. One contender for a viable quantum processor uses lasers to manipulate the very fragile quantum states of trapped ions in a super-cooled vacuum environment. But this approach relies on the extremely careful alignment of free-space optics to deliver light within cryogenic and vacuum environments. The inherent noise involved in such an approach and the need to carefully configure optical systems for each qubit are major barriers to scaling.

As a final project for the class, you will review an experiment in quantum optics anbd describe theory behind it. The goal is to understand how the particular system works and the physics that is explored in the experiment. Possible topics are shown below. Your topic must meet my approval.

Quantum Sensors have applications in a wide variety of fields including microscopy, positioning systems, communication technology, electric and magnetic field sensors, as well as geophysical areas of research such as mineral prospecting and seismology.[4] Many measurement devices utilize quantum properties in order to probe measurements such as atomic clocks, superconducting quantum interference devices, and nuclear magnetic resonance spectroscopy.[4][13] With new technological advancements, individual quantum systems can be used as measurement devices, utilizing entanglement, superposition, interference and squeezing to enhance sensitivity and surpass performance of classical strategies.

Quantum computers are a study of extremes. On the one hand, they promise to be far more powerful than classical machines in solving certain problems. On the other, their quantum nature is remarkably fragile and sensitive to environmental noise. To perform scalable, useful quantum computations, therefore, scientists need to correct these errors in an efficient way. One important step towards this goal is to perform quantum computations in a way that stops correctable errors from spreading (and thus becoming uncorrectable). Now, for the first time, researchers in Austria and Germany have experimentally demonstrated a universal set of these so-called fault-tolerant quantum operations, laying the groundwork for large-scale, error-corrected quantum computation.

Abstract: Practical and useful quantum information processing requires significant advances over current systems in error rates and robustness of basic operations, and at the same time in scale. The high coherence and precise control possible with trapped atomic ion qubits are promising for long-term systems, but the optics required pose a major challenge in scaling. Interfacing low-noise atomic qubits with scalable integrated photonics [1] is a promising route forward, enabling practical extensibility while simultaneously lending robustness to noise. Foundry-fabricated ion trap devices with integrated waveguide optical delivery have recently allowed us to realize multi-ion entangling quantum logic with fidelities competitive with the highest achieved across qubit platforms [2]. Aside from the stability and scalability afforded by these techniques, I will discuss how they allow generation of optical field profiles enabling new physical operations, new photonics motivated by atomic systems broadly, and additional possibilities for such techniques to advance future experiments in areas including sensing and precision metrology.

Bio: Karan Mehta received B.S. Degrees from UCLA in Physics and Electrical Engineering in 2010, and completed his Ph.D. in Electrical Engineering and Computer Science at MIT in 2017. Since 2017 he has been an ETH postdoctoral fellow and subsequently senior scientist in the Physics department at ETH Zurich since 2017. His current research interests include trapped ion techniques, optics and integrated photonics, and quantum information.

Find this paper interesting or want to discuss? Scite or leave a comment on SciRate.AbstractPhysical qubits in experimental quantum information processors are inevitably exposed to different sources of noise and imperfections, which lead to errors that typically accumulate hindering our ability to perform long computations reliably. Progress towards scalable and robust quantum computation relies on exploiting quantum error correction (QEC) to actively battle these undesired effects. In this work, we present a comprehensive study of crosstalk errors in a quantum-computing architecture based on a single string of ions confined by a radio-frequency trap, and manipulated by individually-addressed laser beams. This type of errors affects spectator qubits that, ideally, should remain unaltered during the application of single- and two-qubit quantum gates addressed at a different set of active qubits. We microscopically model crosstalk errors from first principles and present a detailed study showing the importance of using a coherent vs incoherent error modelling and, moreover, discuss strategies to actively suppress this crosstalk at the gate level. Finally, we study the impact of residual crosstalk errors on the performance of fault-tolerant QEC numerically, identifying the experimental target values that need to be achieved in near-term trapped-ion experiments to reach the break-even point for beneficial QEC with low-distance topological codes.

Quantum-enhanced sensing and metrology pave the way for promising routes to fulfil the present day fundamental and technological demands for integrated chips which surpass the classical functional and measurement limits. The most precise measurements of optical properties such as phase or intensity require quantum optical measurement schemes. These non-classical measurements exploit phenomena such as entanglement and squeezing of optical probe states. They are also subject to lower detection limits as compared to classical photodetection schemes. Biosensing with non-classical light sources of entangled photons or squeezed light holds the key for realizing quantum optical bioscience laboratories which could be integrated on chip. Single-molecule sensing with such non-classical sources of light would be a forerunner to attaining the smallest uncertainty and the highest information per photon number. This demands an integrated non-classical sensing approach which would combine the subtle non-deterministic measurement techniques of quantum optics with the device-level integration capabilities attained through nanophotonics as well as nanoplasmonics. In this back drop, we review the underlining principles in quantum sensing, the quantum optical probes and protocols as well as state-of-the-art building blocks in quantum optical sensing. We further explore the recent developments in quantum photonic/plasmonic sensing and imaging together with the potential of combining them with burgeoning field of coupled cavity integrated optoplasmonic biosensing platforms.

To achieve the vision of quantum optical bioscience laboratories on chip will require a sustained and multi-disciplinary research effort. It requires integration of single photon sources with single-molecule sensors and single photon detectors on micro- and nano-structured biochips. It requires the application of advanced optical measurement techniques together with quantum optical measurement protocols to probe various forms of biologically and/or optically active biomatter, as well as single biomolecules in their various functional forms in a suitable (liquid) environment. It requires the application of advanced nano-chemical techniques to spatially and temporally control chemical activity at the level of single molecules and single photons. It requires advances in biophysics to link classical biophysical methods, models and mechanisms to novel, non-classical probing of biophysical activities observed at the levels of single photons and single biomolecular states. It will require the application of quantum-optical analysis techniques to light emitted by biomatter and single molecules in particular. The aim of this review is to provide researchers entering into this exciting multi-disciplinary field with an overview of the state-of-the-art in the various areas of quantum optics research that will need to come together to apply quantum optical methods to biological systems. We will review the areas of research that we have identified as the most relevant for achieving quantum optical bioscience laboratories on a chip: quantum optics, single molecule techniques, nanophotonics and plasmonics, and quantum mechanics of biomatter.

Measuring the photon number Np: Devices which are capable of precisely counting the number of photons at the single-quantum level are of particular importance to QIP. In particular, for applications in linear optics quantum computation [48], [49], the roles of single photonic qubits encompass information storage, communication and computation. They are also essential in quantum-sensing schemes in which the readout stage requires the detection of small numbers of photons with high time resolution. Several factors are generally used to assess a photodetector: (i) Quantum efficiency (QE), i.e. the ratio of the number of photoelectrons collected by the detector to the number of incident photons; (ii) Dead time (recovery time), i.e. the time interval during which the detector is unable to absorb a second photon after the previous photon-detection event; (iii) Dark count rate, associated with the false detection events caused by the dark current in the detector; (iv) Timing jitter, i.e. the deviation of the time interval between the photon absorption and the electrical-pulse generation of the detector; and (v) Photon number resolution, i.e. the capability of distinguishing the photon number [50]. 041b061a72


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