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Basic electronics advice needed, regarding room temperature quantum bit design.

aussiedownunder

May 28, 2021
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Hi guys, I am just an electronics hobbyist so please keep it simple.

I'm working on a room temperature quantum bit design and I'd like some help from people in electronics.

My initial idea is to use an electronically settable potentiometer to set a position, and later read the resultant throughput voltage. The potentiometer would need to be set by a continuous analog signal. Unfortunately I have found they are only available for setting digitally, i.e. in several steps, so not useful here.

A 2nd idea is to emulate the mechanism used in today's working quantum computers. So an electromagnet on a pivot (or using a small motor) could be switched on to rotate up to 180 degrees, its' field position can then alter a nearby FET, the resultant analog voltage FET throughput is the Qbit setting.

So, might the above work to set an analog voltage range? Or is there any known cheap electronic component or system that can be set and read from, as an continuous/analog device.

I will explain more details later if asked, but attempting to keep it short and sweet.

Lloyd
 

Bluejets

Oct 5, 2014
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Analog sensors are iffy in a digital world.
They will wander all over the place and many readings averaged out are needed to get any resemblance of accuracy.
Digital readings are accurate and simple and cheap these days.
I take it that was the idea......???
Other than that cannot follow your idea, perhaps a block diagram or a flow chart would be helpful.
 

aussiedownunder

May 28, 2021
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Analog sensors are iffy in a digital world.
They will wander all over the place and many readings averaged out are needed to get any resemblance of accuracy.
Digital readings are accurate and simple and cheap these days.
I take it that was the idea......???
Other than that cannot follow your idea, perhaps a block diagram or a flow chart would be helpful.
Thanks BJ, So analog sensors will be no use for this project. Accuracy .is needed.

What I'm after is something like an electrically set potentiometer, allowing it to sweep from low to high in a continuous action, not stepped. Is there anything available that does this?

I want to use it as a poor mans QBit, reading the potentiometer adjusted voltage as the (relatively) infinite QBit value.

Is there anything else, or a way to set such an analog range in electronics maybe a stepper motor which can be rigged to turn gradually?

If we can solve this I will build a prototype mini quantum computer, as I'm a computer scientist this is easier, but electronics is a mystery to me.

Again thanks for reply.
 

Bluejets

Oct 5, 2014
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Reading a pot is ok but I thought you were talking analog sensors.
As I said, too hard to follow what it is you need.
Either do a block diagram or a flowchart.

Appears you want to set a reference level via a pot and then use a sensor to give feedback...??
Might be a good idea not to start quoting quantum computers....seems a simple project so why complicate matters.
Big words don't impress around here.
 

Alec_t

Jul 7, 2015
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I can't follow what you're trying to do, but if you just want something that provides an analogue output voltage or current controlled by an electrical or magnetic input then a transistor (bjt or fet), a transformer, an opto-isolator or a Hall-effect sensor could all do that.
 

Harald Kapp

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I think I understand only a fraction of what you're trying to explain and to achieve. Sounds like a form of analog computing. But it seems that this has nothing to do with "quantum" technology. In quantum computing one exploits the the possibility of Qubits to represent several states at the same time by a principle called quantum superposition. This is impossible to achieve on a macroscopic scale with current technology.
I will explain more details later if asked,
I think that is of utter importance for us to understand what you are trying to do.
Or is there any known cheap electronic component or system that can be set and read from, as an continuous/analog device.
There may exist what you are looking for. If only we understood what are trying to do.

The potentiometer would need to be set by a continuous analog signal.
Such a thing doesn't exit - at least as far as I know.
I have found they are only available for setting digitally, i.e. in several steps, so not useful here.
Even a good analog potentiometer's resolution is limited by several factors like the grain of the resistive track, the friction of the mechanical construction etc.
its' field position can then alter a nearby FET, the resultant analog voltage FET throughput is the Qbit setting.
ad 1: FETs are not magnetically sensitive.
ad2: As mentioned above a Qbit doesn't have a defined setting (unless you evaluate the result of a quantum computation), rather a Qubit represents a superposition of several states, not possible to achieve on a macroscopic scale with current technology.
 

hevans1944

Hop - AC8NS
Jun 21, 2012
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I'm working on a room temperature quantum bit design
Oh, really? There has been some recent work done in this area, using laser-excited point-defects in diamond crystal lattices and in silicon carbide crystals. Anyone interested in that could start here. I don't see any practical applications of this yet. Qubits tend to "evaporate" because of interaction with their environment. That is why most serious work toward development of a quantum computer requires cryogenic temperatures near absolute zero.

... I will build a prototype mini quantum computer, as I'm a computer scientist this is easier...
Well, of course you will! A computer scientist doesn't need a real computer if the goal is simply to design algorithms, or whatever it is a computer scientist does to keep busy and occupy time. In fact, the availability of a real computer can be a handicap, since those invariably require programming... an exercise best left to a student... and some understanding of electronics input and output mechanisms.

As for an analog voltage-controlled potentiometer with a continuously variable output, which seems to be what you are searching for, these exist in most SPICE-based simulation programs. There are also hardware photo-resistive devices that can be used as potentiometers controlled by voltage-controlled LED currents, the LED serving as a variable intensity light source. And of course there is that World War II standby: analog servomechanisms. Those are still used today, but their response to real-time analog command inputs is rather slow, somewhat the opposite of what a quantum computer will do.

I used one of those little photo-resistor gems some fifty years ago to sense and measure the position of a balance beam mechanism that applied isotonic (constant restraining force) tensile stress to a live, freshly dissected, frog muscle tissue as it was electrically stimulated to contract. A motor-driven weight slid along a lead-screw attached to the balance-beam, which through a series of low-friction levers and pulleys applied the required tension for the experiment. A small load-cell measured the force created by the electrically stimulated muscle fiber. All data collected was in analog form and "stored" as traces on a multi-channel strip-chart recorder.

A separate "tension motor" stretched the muscle tissue before stimulation until the balance-beam reached it's "zero" or balanced position. IIRC, I illuminated this photo-resistor with a slit, illuminated by an ordinary incandescent lamp. The position of the slit image on the photo-resistor was linearly related to the balance-beam position, and a feedback system caused the "tension motor" to stretch the muscle fiber until the balance-beam was maintained at its balanced position.

This was one of many interdisciplinary projects I worked on early in my career. We had no microprocessors, and minicomputers were waaay too expensive, so just about everything we built was based on analog electronics, sometimes supplemented with transistor-transistor logic or diode-relay logic for control functions.

As several other EP posters have requested, please tell us WTF you are trying to DO, so we can offer useful suggestions.
 
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