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1500 questions
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Physical meaning of twirling in Randomized Benchmarking
I was reading papers on Randomized Benchmarking, such as this and this.
(more specifically, equation 30 in the second paper)
It appears to be some kind of averaging but I would like to have a more intuitive and physical picture of what it actually…
Blackwidow
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9
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What does it mean for a quantum computer to have $X$ qubits?
I want to preface with a disclaimer that I am a physicist with minimal knowledge of computer hardware. I have a solid understanding of quantum information from a theoretical standpoint but zero knowledge of how it is implemented. Here goes...
When a…
Jackson
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9
votes
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What about BosonSampling can be publicly verified?
Boson Sampling, sometimes stylized as BosonSampling, is an attractive candidate problem to establish quantum supremacy; the engineering problems appear more surmountable than those associated with a Turing-complete quantum computer.
However, Boson…
Mark Spinelli
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9
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What exactly is "matrix sparsity" $s$?
In many sources (like on Page 30 here), I found that the complexity of the original Harrow Hassidim Lloyd is stated as $\mathcal{O}(\log (N) s^2 \kappa^2/\epsilon)$ where $s$ is said to be the "matrix sparsity". What is a precise definition of the…
Sanchayan Dutta
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9
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1 answer
Is SO(2) with any entangling gate universal?
Let $E \in SU(2^k)$ be any entangling gate (for some $k \geq 2)$. Then my question is simply whether or not it is known that $SO(2) \cup \{ E \}$ is universal for $\mathsf{BQP}$?
Clearly it seems that this ought to be true, in light of the standard…
Mary_Smith
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9
votes
2 answers
Can we perform quantum mechanical simulations using a quantum computer?
I'm a computer science major who's really keen on physics and quantum mechanics. I have started learning about Q# and D-Wave, but I just wanted to know if it's possible to test quantum mechanical theories using quantum computers.
If so, then what…
Yashank
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9
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Possibility of a "reset" quantum gate
I wish to have a "reset" gate. This gate would have an effect to bring a qubit to the $\mid0\rangle$ state.
Clearly, such a gate is not unitary (and so I'm unable to find any reliable implementation in terms of universal gates).
Now for my…
Ntwali B.
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9
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1 answer
What are the preferred numerical methods to simulate the evolution of a state through a time-dependent Hamiltonian?
Under the influence of a time-independent Hamiltonian $H$, a state $|\psi\rangle$ will evolve after a time $t$ to the final state $|\psi(t)\rangle=e^{-iH t}|\psi\rangle$, while in the most general case of a time-dependent Hamiltonian $H(t)$, the…
glS
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9
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2 answers
Resources for Quantum Communication Complexity
I recently came to know about this interesting topic of "communication complexity". In simple words, Wikipedia defines it as:
In theoretical computer science, communication complexity studies the
amount of communication required to solve a…
Sanchayan Dutta
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9
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Are there any other companies besides Microsoft pursuing topological QC?
Also, why is Microsoft placing such an emphasis on topological qubits when most other companies seem to be focusing on other qubit technologies?
I know topological qubits could handle noise far better than other systems, so they are appealing, but…
jman
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9
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1 answer
How to verify whether a state is a stabilizer state?
Given an arbitrary $n$-qudit state vector $|\psi\rangle =\sum_i c_i| i \rangle \in \mathbb{C}_d^n$ for some orthonormal basis $\{|i\rangle\}$, what is the most efficient way one can:
Verify whether the state is a stabilizer state (i.e. can be…
SLesslyTall
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9
votes
3 answers
Does conditional gate collapse controller's superposition?
I've created a simple circuit in Q-Kit to understand conditional gates and outputted states on each step:
In the beginning there is clear 00 state, which is the input
The first qubit is passed through the Hadamard gate, it gets into superposition,…
CodeSandwich
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9
votes
2 answers
Topological Circuit Simulator
Does something like Quirk exist for topological (eg. braided) circuits?
Alternatively, any ideas on how @CraigGidney is getting these circuits (or something similar)?
user820789
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9
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What exactly is a subsystem code?
I'm sure I'm just tripping up on terminology here. I'm new to the wonderful field of QEC, and so far am familiar with the stabiliser formalism and basic codes such as the generic surface code. I keep seeing references in the [vast] literature to…
user23402
9
votes
1 answer
What does "lift" mean in the Lifted Product (LP) Code?
I am watching this talk about Lifted Product Code (LP). For me, it's quite straightforward to see how to construct a HyperGraph Product Code (HGP) using two separate classical codes. However, I failed to grasp the idea of lifting and how this could…
Yunzhe
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