Trying to get my head round quantum computers

[Fusion]

Which gives the possibility of faster than light communication, in theory.

Not true:

https://en.wikipedia.org/wiki/No-communication_theorem

 

[Orionaut]

Quantum entanglement presumably. Two particles that are entangled can influence each other even when on opposite sides of the universe. Which gives the possibility of faster than light communication, in theory.

I think the issue with FTL comms is that although the entanglement can be FTL, the separation of the particles can not be.

However, If you sent a spacecraft to Pluto with a store of entangled particles with their partners remaining on earth, could we use FTL comms until they "run out"??

 

[wolfie138]

In practice, one cannot detect an electron without interfering with it. The image of a detector somehow pointed at the slit to detect the passage of an electron is not possible in practice. The only way to detect an electron is to have some physical interaction with it. So we aren't simply observing the electron's state, we are interferring with it's state. Is it any wonder that this physical interaction destroys the interference pattern?

how do you know you're interfering w/ it if you don't know its state beforehand?

 

[rubberduck]

Hello again. I have been trying to dig in to (watch youtube videos on) Pilot wave theory / Bohmian mechanics. While I get the basic principle (or at least I think I do) I do not understand how this theory explains how the interference pattern from the double slit experiment disappears should a detection device be place after the slits. Surely the whole pilot wave cannot collapse can it? And if so is it really that much different from Copenhagen interpretation?

 

[rubberduck]

Hello again... In my efforts to expand my brain I stumbled on a youtube channel called 'PBS Space Time'... It is fantastic for the armchair physicist... I need to watch some videos multiple times, do background reading and even then dont 100% understand but there are some great videos on there.

 

[itchy]

Its easy its basic computational maths.

The is 1 and 0 with quantum computing the is a 3rd bit 0 and 1 combined so the is 3 bits as opposed to 2 bits.

3 bits don't go into 10 so binary base 10 goes a bit wobbly that's all it is, I can understand how its hard to comprehend but you need to look at the bigger picture.

 

[rubberduck]

Its easy its basic computational maths.

The is 1 and 0 with quantum computing the is a 3rd bit 0 and 1 combined so the is 3 bits as opposed to 2 bits.

3 bits don't go into 10 so binary base 10 goes a bit wobbly that's all it is, I can understand how its hard to comprehend but you need to look at the bigger picture.

You are wrong... I used to think that way but it is not as simple as computers being able to switch to base 3 number processing as opposed to binary... It is more than that in terms of problem solving.

 

[itchy]

You are wrong... I used to think that way but it is not as simple as computers being able to switch to base 3 number processing as opposed to binary... It is more than that in terms of problem solving.

Am not wrong base number 12 goes into 3 so you have 2 bits extra in quantum computing. Hence the computational advantage as the is an extra 2 bits.

 

[itchy]

So it would be 1,2,4,8,16,32,64,128.256,512,1024,2048,4096,8192. In binary.

As opposed to 16 bit or 32bit which is you know the numbers.....

 

[rubberduck]

No, I don't think that is right m8.

 

[itchy]

No, I don't think that is right m8.

You could be right but its my interpretation of quantum computing.

Its either on or off but as its quantum it could be either state, so its one of them things that's hard to constitute a meaning.

Swings and roundabouts so to say.

 

[itchy]

In fact it could be a quadratic formula so the would be more bits??

Its a messy subject that's for sure.

 

[Rroff]

Looking at quantum computing in terms of bits is very misleading and trying to understand it through bits doesn't work - you need to understand how it works before you can understand the context of bits.

 

[itchy]

Looking at quantum computing in terms of bits is very misleading and trying to understand it through bits doesn't work - you need to understand how it works before you can understand the context of bits.

Computers are bits and bytes so its either on or off but with quantum computing its 2 states, on and off at the same time which screws things up.

 

[Rroff]

It isn't on/off its 0,1 you can't (simplistically) have a void/null state - it is more closely an approximate of a coordinate system than classical bits.

 

[wolfie138]

the more people try and explain this, the more it sounds like complete made-up ********

 

[D.P.]

You could be right but its my interpretation of quantum computing.

Its either on or off but as its quantum it could be either state, so its one of them things that's hard to constitute a meaning.

Swings and roundabouts so to say.

Your interpretation is far form the mark. For starters, better to think of the superposition to be between 0 and 1, not both.

But to realize the power of a quantum co outer you have to realize a digital compute is in only 1 state at a time, while a quantum is in a superpositon of all states. For example a digital computer with 8 bits can represent 2^8=256 different numbers, but could only set its state to 1 of them at a time. If your task was to search all 256 numbers for a special one, e.g., password, you would test each of the 256 in sequence. In a quantum computer with 8 qubits, the system will be in all 256 states at the same time and thus there will be no iteration required
, if an approrpiate quantum algorithm can be defined (often it cant).

Also, quantum lagortigms are frequently only probabalistic, with correct results being fund only within certain bounds and probabilities.

 

[itchy]

Your interpretation is far form the mark. For starters, better to think of the superposition to be between 0 and 1, not both.

But to realize the power of a quantum co outer you have to realize a digital compute is in only 1 state at a time, while a quantum is in a superpositon of all states. For example a digital computer with 8 bits can represent 2^8=256 different numbers, but could only set its state to 1 of them at a time. If your task was to search all 256 numbers for a special one, e.g., password, you would test each of the 256 in sequence. In a quantum computer with 8 qubits, the system will be in all 256 states at the same time and thus there will be no iteration required
, if an approrpiate quantum algorithm can be defined (often it cant).

Also, quantum lagortigms are frequently only probabalistic, with correct results being fund only within certain bounds and probabilities.

Not really as in quantum mechanics it changes disposition when observed, its like schroeder's cat so to say.