Most Popular
1500 questions
43
votes
7 answers
Why is it harder to build quantum computers than classical computers?
Is it because we don't know exactly how to create quantum computers (and how they must work), or do we know how to create it in theory, but don't have the tools to execute it in practice? Is it a mix of the above two? Any other reasons?
Archil Zhvania
- 2,187
- 1
- 20
- 31
43
votes
2 answers
What is the "surface code" in the context of quantum error correction?
I am studying Quantum Computing and Information, and have come across the term "surface code", but I can't find a brief explanation of what it is and how it works. Hopefully you guys can help me with this.
Ivanovitch
- 623
- 1
- 6
- 7
43
votes
4 answers
Is there any general statement about what kinds of problems can be solved more efficiently using a quantum computer?
Is there a general statement about what kinds of problems can be solved more efficiently using quantum computers (quantum gate model only)? Do the problems for which an algorithm is known today have a common property?
As far as i understand quantum…
hiro protagonist
- 533
- 7
- 12
41
votes
3 answers
The algorithm of the new quantum factoring record 1,099,551,473,989
According to the New Scientist News, the Zapata team is able to factor 1,099,551,473,989 into its factors 1,048,589 and 1,048,601.
According to the New Scientist:
A quantum computing start-up company called Zapata has worked with IBM to develop a…
kelalaka
- 709
- 1
- 6
- 17
40
votes
2 answers
What is quantum gate teleportation?
Quantum state teleportation is the quantum information protocol where a qubit is transferred between two parties using an initial shared entangled state, Bell measurement, classical communication and local rotation. Apparently, there is also…
Kiro
- 1,975
- 16
- 24
39
votes
8 answers
If all quantum gates must be unitary, what about measurement?
All quantum operations must be unitary to allow reversibility, but what about measurement? Measurement can be represented as a matrix, and that matrix is applied to qubits, so that seems equivalent to the operation of a quantum gate. That's…
auden
- 3,429
- 1
- 20
- 48
38
votes
4 answers
Is there a layman's explanation for why Grover's algorithm works?
This blogpost by Scott Aaronson is a very useful and simple explanation of Shor's algorithm.
I'm wondering if there is such an explanation for the second most famous quantum algorithm: Grover's algorithm to search an unordered database of size…
Discrete lizard
- 3,124
- 2
- 19
- 41
37
votes
13 answers
Currently, what are the best structured courses available online on quantum computing?
As we make inroads into Machine Learning, there seem to be plenty of respectable courses available online via Coursera, edX, etc. on the topic. As quantum computing is still in its infancy, not to mention, incredibly daunting, it is vital that easy…
Ebony Maw
- 535
- 1
- 4
- 7
37
votes
6 answers
If quantum speed-up is due to the wave-like nature of quantum mechanics, why not just use regular waves?
The intuition I have for why quantum computing can perform better than classical computing is that the wavelike nature of wavefunctions allow you to interfere multiple states of information with a single operation, which theoretically could allow…
Steven Sagona
- 1,119
- 7
- 16
37
votes
3 answers
Can a quantum computer simulate a normal computer?
Similar to the question Could a Turing Machine simulate a quantum computer?: given a 'classical' algorithm, is it always possible to formulate an equivalent algorithm which can be performed on a quantum computer? If yes, is there some kind of…
Glorfindel
- 620
- 1
- 9
- 24
37
votes
3 answers
How do you write a simple program for a D-Wave device?
I would like to know how a job for a D-Wave device is written in code and submitted to the device.
In the answer it would be best to see a specific example of this for a simple problem. I guess that the "Hello World" of a D-Wave device would be…
James Wootton
- 11,272
- 1
- 31
- 72
36
votes
5 answers
Introductory material for quantum machine learning
In the past few days, I have been trying to collect material (mostly research papers) related to Quantum machine learning and its applications, for a summer project. Here are a few which I found interesting (from a superficial…
Sanchayan Dutta
- 17,497
- 7
- 48
- 110
36
votes
4 answers
What is meant by the term "computational basis"?
What is meant by the term "computational basis" in the context of quantum computing and quantum algorithms?
user1039
36
votes
2 answers
Why is a quantum computer in some ways more powerful than a nondeterministic Turing machine?
The standard popular-news account of quantum computing is that a quantum computer (QC) would work by splitting into exponentially many noninteracting parallel copies of itself in different universes and having each one attempt to verify a different…
tparker
- 2,711
- 11
- 26
36
votes
1 answer
How are quantum gates implemented in reality?
Quantum gates seem to be like black boxes. Although we know what kind of operation they will perform, we don't know if it's actually possible to implement in reality (or, do we?). In classical computers, we use AND, NOT, OR, XOR, NAND, NOR, etc…
Sanchayan Dutta
- 17,497
- 7
- 48
- 110