The lock-in amplifier allows tiny signals from sensors to be captured with precision despite unavoidable noise limitations and other test and measurement challenges of the signal chain. Part 1 of this article looked at the changes of capturing low-level signals such as from a photodetector despite unavoidable signal-path noise, drift, offsets, and other imperfections. This […]
FAQ
Understanding the lock-in amplifier, Part 1: The sensing challenge
The lock-in amplifier allows tiny signals from sensors to be captured with precision despite unavoidable noise limitations and other signal-chain test and measurement challenges. There are some basic test and measurement instruments common to scientific labs and engineering benches of all types, whether electronic, biomedical, chemical, optical, or mechanical. Among these are the digital voltmeter, […]
Applications and algorithms for quantum computing
Developing the hardware for quantum computing and hybrid quantum/classical computing systems is only one step in developing practical quantum computing solutions. Development of quantum algorithms and related software programming of the qubits is required to implement practical applications using quantum approaches to computing. Earlier FAQs in this series looked at the basics of quantum computing, […]
Online calculators that are handy for EEs
Online calculators have proliferated. Consider that one site dubbed omnicalculator.com now hosts over 1,800 online calculators in various disciplines. But when it comes to electronics and engineering, the pickings are slimmer. Calculatoredge.com provides numerous online calculators for engineers of which a little over 100 are in electronics and electrical engineering. That brings us to Digi-Key […]
Merging quantum and classical computing in a hybrid system
Practical quantum computing requires connections to the outside world. Those connections may be for collaboration between a quantum computer and an external computing resource such as a supercomputer. They can simply output the results of the quantum computations in a manner accessible and usable by human operators. In either case, there’s a paradox between the […]
What are the basics of quantum computing?
The concept of quantum computing has been around since the early 1980s when physicist Paul Benioff proposed a quantum mechanical model of the Turing machine. Benioff’s ideas were built upon by Richard Feynman, Yuri Manin, and others, who suggested that a quantum computer had the potential to simulate things that can’t be done using classical […]
What is the difference between variable reluctance and eddy current speed sensors?
Both variable reluctance (VR) and eddy current (EC) technologies provide contactless speed sensors based on interaction with a magnetic field. A variable reluctance sensor can be thought of as an ac generator with an output voltage proportional to speed. With its self-generating electrical signal, a VR sensor does not require an external power supply. The […]
Quantum computing system architectures
There are a variety of possible physical embodiments of quantum computers. This FAQ will explore several of those possibilities. Qubits, Hamiltonians, and decoherence are three important concepts needed when discussing various approaches to quantum computing. Check out the first FAQ in this series for a more detailed discussion of “What are the basics of quantum […]
Lissajous figures: From math to measurement to art, Part 3
Parts 1 and 2 looked at the equations, history, and technical role of Lissajous figures. This final part will look at their use in graphics and art. One widely known use was in the opening sequence of award-winning legendary TV series The Outer Limits (1963 to 1965) with its classic voice-over audio “Do not attempt […]
Lissajous figures: From math to measurement to art, Part 2
The Lissajous figures of Part 1 were interesting but of little apparent practical use, but that is not the case. Until the availability of high-accuracy instrumentation for frequency measurement, Lissajous figures served a major role in frequency measurement and assessment. How so? Today, if you want to measure the resonant frequency of a crystal used […]