Hey guys, I learned electronics from a nobel laureate! Throughout my physics career including PhD, analog electronics was the most difficult but probably also the most rewarding class to me. I fondly remember staying until 2am in broida at ucsb trying to get a filter to work, getting a few hours sleep, then being back in the lab before sunrise. Of course, this was mostly the result of procrastination, but damn were t…
"Of course, good voltage sources vary their resistance just like good current sources vary their voltage. "
Did you mean to say "good voltage sources vary their current just like good current sources vary their voltage"?
(I know nobody really cares, and I promise I'll seek help for whatever neurological condition I seem to have.)
Hey guys, I learned electronics from a nobel laureate! Throughout my physics career including PhD, analog electronics was the most difficult but probably also the most rewarding class to me. I fondly remember staying until 2am in broida at ucsb trying to get a filter to work, getting a few hours sleep, then being back in the lab before sunrise. Of course, this was mostly the result of procrastination, but damn were t…
"Of course, good voltage sources vary their resistance just like good current sources vary their voltage. " Did you mean to say "good voltage sources vary their current just like good current sources vary their voltage"? (I know nobody really cares, and I promise I'll seek help for whatever neurological condition I seem to have.)
There are two different ways to produce a voltage source. The first is to put a variable resistor in series with the power source, which you can adjust to control the voltage. This works, but dissipates a lot of heat. The second is to put a switch in series with the power source and a capacitor in parallel with the load, then switch the power source on and off very rapidly and use the duty cycle to control the voltage. This is how modern switching power supplies work. In actual practice, there are also inductors in the circuit which cause resonance, and allow the switching to happen when there is no current flowing through the switch. This is how modern switching power supplies can be so efficient.
This award involved some clever engineering to set up quantum effects in a macroscopic system, but was there any new physics involved here? (Still better than last year's award which wasn't really physics at all!)
This could be one of the building blocks of quantum computing. You can have a macro system behave in quantum way.
This is a practical implementation of something that was only theoretically possible or observed on very small scale.
"Of course, good voltage sources vary their resistance just like good current sources vary their voltage. " Did you mean to say "good voltage sources vary their current just like good current sources vary their voltage"? (I know nobody really cares, and I promise I'll seek help for whatever neurological condition I seem to have.)
There are two different ways to produce a voltage source. The first is to put a variable resistor in series with the power source, which you can adjust to control the voltage. This works, but dissipates a lot of heat. The second is to put a switch in series with the power source and a capacitor in parallel with the load, then switch the power source on and off very rapidly and use the duty cycle to control the voltag…
Ok, thanks. But I was calling attention to a point in the previous comment that makes it difficult to see a kind of "dualism" between idealized current sources to idealized voltage sources. Idealized current or voltage sources don't necessarily have any series resistance, and it doesn't matter how they're realized.
There are two different ways to produce a voltage source. The first is to put a variable resistor in series with the power source, which you can adjust to control the voltage. This works, but dissipates a lot of heat. The second is to put a switch in series with the power source and a capacitor in parallel with the load, then switch the power source on and off very rapidly and use the duty cycle to control the voltag…
Ok, thanks. But I was calling attention to a point in the previous comment that makes it difficult to see a kind of "dualism" between idealized current sources to idealized voltage sources. Idealized current or voltage sources don't necessarily have any series resistance, and it doesn't matter how they're realized.
Your point is well taken. My guess was that the OP had implementation in mind when they wrote "good voltage sources vary their resistance".
More than deserved! Both Devoret and Martinis are also highly involved in pushing quantum engineering to new levels - Devoret at Google Quantum AI and Martinis (formerly at Google) with his company, Qolab. Coincidentally, I have a close friend doing his PhD with Devoret and know someone working with Martinis. I am curious to see if they will ever see their respective supervisors again, given that the Nobel Prize atte…
Definitely agree! It's just strange seeing Devoret without Schoelkopf!
It is worth noting that the research that Martinis is being awarded the Nobel prize was largely performed while at NIST (National Institute of Standards and Technology), part of the Dept of Commerce.
Dumb question: "We know that the ball will bounce back every time it is thrown at a wall. A single particle, however, will sometimes pass straight through an equivalent barrier in its microscopic world and appear on the other side. This quantum mechanical phenomenon is called tunnelling." Is the particle just failing to collide with the wall since objects are mostly empty space? Or is something more spooky or interes…
The simplest version of this problem involves a "potential barrier." Another loose classical analogy here is considering a ball rolling towards a hill. Everyone knows from experience in classical systems that with sufficient speed i.e. kinetic energy, the ball can go over the hill i.e. there is more kinetic energy in the ball when it meets the bottom of the hill than there is potential energy the ball would have at the top of the hill. If it has less energy, it will not make it past the hill. The weird thing about the analogous situation in quantum mechanics is that even if the particle has less energy than the potential barrier (the hill), it has a non-zero probability of being on the other side due to the wave function exponentially decaying in the barrier.
Dumb question: "We know that the ball will bounce back every time it is thrown at a wall. A single particle, however, will sometimes pass straight through an equivalent barrier in its microscopic world and appear on the other side. This quantum mechanical phenomenon is called tunnelling." Is the particle just failing to collide with the wall since objects are mostly empty space? Or is something more spooky or interes…
As far as I know, the "single particle" referred to here is not a "classical particle" like a ball. It's a "quantum object" that, depending on how you look at it, behaves like a wave or an object. Definitely spooky!