Linked by Thom Holwerda on Tue 15th Aug 2017 23:21 UTC
Hardware, Embedded Systems

This paper is a gentle but rigorous introduction to quantum computing intended for computer scientists. Starting from a small set of assumptions on the behavior of quantum computing devices, we analyze their main characteristics, stressing the differences with classical computers, and finally describe two well-known algorithms (Simon's algorithm and Grover's algorithm) using the formalism developed in previous sections. This paper does not touch on the physics of the devices, and therefore does not require any notion of quantum mechanics.

Some light reading before bedtime.

Thread beginning with comment 648023
To view parent comment, click here.
To read all comments associated with this story, please click here.
RE[3]: Worthless.
by Megol on Wed 16th Aug 2017 10:19 UTC in reply to "RE[2]: Worthless."
Megol
Member since:
2011-04-11

Hi,

"This is just idiotic crap. There have been many important computers that can't wait for users to put in numbers. The idea that it somehow is a practical requirement just shows how thoroughly stupid and arrogant you are.

Learn something about computing before writing anything else please - this is embarrassing!


If you don't understand the difference between one of many possible examples of "something that real software might actually want to do" and an absolute fundamental requirement; then you lack the minimum amount of intelligence needed to form a valid comment.
"

WHERE THE F*CK DO YOU GET THE IDIOTIC IDEA QUANTUM COMPUTERS IN ANY WAY OR FORM ARE INTENDED TO REPLACE NORMAL COMPUTER?!?

They aren't. For traditional algorithms (many of which will _not_ be accelerated by quantum computers) they don't make sense. They would be more expensive, they would be too big (they require near-absolute zero temperatures in any practical system), they would be "clocked" much lower and they can't scale in memory or processing width. This is basics.

You are talking about assembly as if that is something defining a computer. It isn't. The ISA may be seen as something defining a computer.

Many computers have no assembly language. I have one standing ~5m from me right now.

And to continue there are many computers with no (human) IO at all. It have no bearing on how practical the computer is which anybody that have done even basic reading about computers and computation would know.
And there have been many systems when the main computer have no I/O capabilities in itself instead using secondary I/O subsystems for all external communication.

So I repeat: learn about computers and computer architecture before thinking a quantum computer have to be a replacement for a crap design like IBM PC compatibles.

Reply Parent Score: 2

RE[4]: Worthless.
by Thom_Holwerda on Wed 16th Aug 2017 10:33 in reply to "RE[3]: Worthless."
Thom_Holwerda Member since:
2005-06-29

So I repeat: learn about computers and computer architecture before thinking a quantum computer have to be a replacement for a crap design like IBM PC compatibles.


When all you have is a hammer, every problem looks like a nail.

Virtually everyone in the world is only familiar with 'regular' computers. It's to be expected most of us are completely and utterly ignorant when an entirely different form of computing comes along.

Reply Parent Score: 2

RE[5]: Worthless.
by Kochise on Wed 16th Aug 2017 10:36 in reply to "RE[4]: Worthless."
Kochise Member since:
2006-03-03

Just like imperative vs. functional programming.

Reply Parent Score: 2

RE[5]: Worthless.
by project_2501 on Wed 16th Aug 2017 10:50 in reply to "RE[4]: Worthless."
project_2501 Member since:
2006-03-20

a good example is this:

Task - brute force test a password

Normal computing - try each test password, one after another, will take a long time for strong passwords/crypto

Quantum computing - a waveform superposition of all possible passwords will collapse to the correct answer. in one step. no need to try each and every password one after another.

This is why quantum computing scares security people ..

The core of quantum computation is the collapsing of many possible answers into the right set of anwers - instantaneously.

Proper parellism.

Reply Parent Score: 4

RE[4]: Worthless.
by Brendan on Wed 16th Aug 2017 12:17 in reply to "RE[3]: Worthless."
Brendan Member since:
2005-11-16

Hi,

WHERE THE F*CK DO YOU GET THE IDIOTIC IDEA QUANTUM COMPUTERS IN ANY WAY OR FORM ARE INTENDED TO REPLACE NORMAL COMPUTER?!?


Nowhere. I've said no such thing, and you made this up yourself. I've only assumed that "quantum computing" means that its suitable for computing (as opposed to a special purpose "fixed function" device, like an old analogue FM radio circuit).

They aren't. For traditional algorithms (many of which will _not_ be accelerated by quantum computers) they don't make sense. They would be more expensive, they would be too big (they require near-absolute zero temperatures in any practical system), they would be "clocked" much lower and they can't scale in memory or processing width. This is basics.


You think this is relevant? Either it can perform arbitrary computation (even if it does so extremely slowly) or it can't perform arbitrary computation.

You are talking about assembly as if that is something defining a computer. It isn't. The ISA may be seen as something defining a computer.


I'm not defining a computer, I'm defining a processor (which is only one piece of a computer). The operations ("instructions") that a processor can perform are what define a processor.

Many computers have no assembly language. I have one standing ~5m from me right now.


Then it's not a computer.

Think of a Turing Machine. One of the main properties is that you can change the tape (that contains the program it executes) and change the behaviour of the machine. That tape contains something to indicate which operations to perform in which order (the machine code of the Turing machine).

This is one of the main problems with all the "quantum computing" rhetoric - they never describe what a program for a quantum computer is. Somehow an algorithm just magically appears out of nowhere, does something with some data that also appears out of nowhere, finds a result, and then everything is suddenly forgotten with no mention of any kind of output and no mention of any way for anything external to obtain the result.

And to continue there are many computers with no (human) IO at all.


Imagine if I said "Some integers are even (e.g. 4)" and you spent several hours whining that 6 is also an even integer because you lacked the intelligence to understand the difference between one of many possible examples and a fundamental requirement. Then imagine I tried to point out how stupid you are, but your intelligence is so low that you couldn't get the hint and continued whining that 6 is also an even integer.

This is very much like that. I said something about "get 2 numbers from user, add them and show the result" in one of multiple possible examples (where several other examples didn't involve a user at all), and you're still whining about "(human) IO" several hours later. Human IO is not a fundamental requirement (it's just one example of "something that might be useful") in the same way that being equal to 4 is not a requirement that all even integers must have.

And there have been many systems when the main computer have no I/O capabilities in itself instead using secondary I/O subsystems for all external communication.


Anyone with more intelligence than a mouldy potato would have realised that a computer with no IO capabilities of its own would have no way to communicate with a secondary IO subsystem.

- Brendan

Reply Parent Score: 3

RE[5]: Worthless.
by sj87 on Wed 16th Aug 2017 16:55 in reply to "RE[4]: Worthless."
sj87 Member since:
2007-12-16

Nowhere. I've said no such thing, and you made this up yourself. I've only assumed that "quantum computing" means that its suitable for computing (as opposed to a special purpose "fixed function" device, like an old analogue FM radio circuit).

You see term "quantum computing" and because it includes the word "computing", you then equate it to any form of computing? LOL!

The use-cases you initially described have nothing to do with quantum computing. Waiting for user input or reading from a block device isn't bottlenecked by computational power.

Bubble sort is an algorithm that likely won't be meaningful with quantum processors just like it isn't meaningful with GPUs of modern day. At best it can be optimized to be run partially in a CPU and partially in a GPU... Now try replacing 'GPU' with 'Quantum Processing Unit' in the previous sentence and take a moment to think about it.

Edited 2017-08-16 16:56 UTC

Reply Parent Score: 2