32 research outputs found

    Probing quantum devices with radio-frequency reflectometry

    Get PDF
    Many important phenomena in quantum devices are dynamic, meaning that they cannot be studied using time-averaged measurements alone. Experiments that measure such transient effects are collectively known as fast readout. One of the most useful techniques in fast electrical readout is radio-frequency reflectometry, which can measure changes in impedance (both resistive and reactive) even when their duration is extremely short, down to a microsecond or less. Examples of reflectometry experiments, some of which have been realized and others so far only proposed, include projective measurements of qubits and Majorana devices for quantum computing, real-time measurements of mechanical motion, and detection of non-equilibrium temperature fluctuations. However, all of these experiments must overcome the central challenge of fast readout: the large mismatch between the typical impedance of quantum devices (set by the resistance quantum) and of transmission lines (set by the impedance of free space). Here, we review the physical principles of radio-frequency reflectometry and its close cousins, measurements of radio-frequency transmission and emission. We explain how to optimize the speed and sensitivity of a radio-frequency measurement and how to incorporate new tools, such as superconducting circuit elements and quantum-limited amplifiers into advanced radio-frequency experiments. Our aim is threefold: to introduce the readers to the technique, to review the advances to date, and to motivate new experiments in fast quantum device dynamics. Our intended audience includes experimentalists in the field of quantum electronics who want to implement radio-frequency experiments or improve them, together with physicists in related fields who want to understand how the most important radio-frequency measurements work

    Applications and Experiences of Quality Control

    Get PDF
    The rich palette of topics set out in this book provides a sufficiently broad overview of the developments in the field of quality control. By providing detailed information on various aspects of quality control, this book can serve as a basis for starting interdisciplinary cooperation, which has increasingly become an integral part of scientific and applied research

    Can my chip behave like my brain?

    Get PDF
    Many decades ago, Carver Mead established the foundations of neuromorphic systems. Neuromorphic systems are analog circuits that emulate biology. These circuits utilize subthreshold dynamics of CMOS transistors to mimic the behavior of neurons. The objective is to not only simulate the human brain, but also to build useful applications using these bio-inspired circuits for ultra low power speech processing, image processing, and robotics. This can be achieved using reconfigurable hardware, like field programmable analog arrays (FPAAs), which enable configuring different applications on a cross platform system. As digital systems saturate in terms of power efficiency, this alternate approach has the potential to improve computational efficiency by approximately eight orders of magnitude. These systems, which include analog, digital, and neuromorphic elements combine to result in a very powerful reconfigurable processing machine.Ph.D

    Design of RF/IF analog to digital converters for software radio communication receivers

    Get PDF
    Software radio architecture can support multiple standards by performing analogto- digital (A/D) conversion of the radio frequency (RF) signals and running reconfigurable software programs on the backend digital signal processor (DSP). A slight variation of this architecture is the software defined radio architecture in which the A/D conversion is performed on intermediate frequency (IF) signals after a single down conversion. The first part of this research deals with the design and implementation of a fourth order continuous time bandpass sigma-delta (CT BP) C based on LC filters for direct RF digitization at 950 MHz with a clock frequency of 3.8 GHz. A new ADC architecture is proposed which uses only non-return to zero feedback digital to analog converter pulses to mitigate problems associated with clock jitter. The architecture also has full control over tuning of the coefficients of the noise transfer function for obtaining the best signal to noise ratio (SNR) performance. The operation of the architecture is examined in detail and extra design parameters are introduced to ensure robust operation of the ADC. Measurement results of the ADC, implemented in IBM 0.25 µm SiGe BiCMOS technology, show SNR of 63 dB and 59 dB in signal bandwidths of 200 kHz and 1 MHz, respectively, around 950 MHz while consuming 75 mW of power from ± 1.25 V supply. The second part of this research deals with the design of a fourth order CT BP ADC based on gm-C integrators with an automatic digital tuning scheme for IF digitization at 125 MHz and a clock frequency of 500 MHz. A linearized CMOS OTA architecture combines both cross coupling and source degeneration in order to obtain good IM3 performance. A system level digital tuning scheme is proposed to tune the ADC performance over process, voltage and temperature variations. The output bit stream of the ADC is captured using an external DSP, where a software tuning algorithm tunes the ADC parameters for best SNR performance. The IF ADC was designed in TSMC 0.35 µm CMOS technology and it consumes 152 mW of power from ± 1.65 V supply

    Low Power CMOS Interface Circuitry for Sensors and Actuators

    Get PDF

    Spatial time domain reflectometry for monitoring transient soil moisture profiles

    Get PDF
    corecore