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18
votes
5 answers
What is a Bacon-Shor code and what is its significance?
I'm at the AQC conference at NASA and everybody seems to suddenly be talking about the Bacon-Shor code but there is no Wikipedia page and the pdf that I gave a link to does not really explain what it is and how it works.
How does it compare to the…
user1271772 No more free time
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18
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How to implement the 4 Bell states on the IBM Q (composer)?
I would like to simulate the 4 "Bell States" on the IBM composer?
How can I best implement those 4 Bell states using the existing set of gates ?
Here below you see the definition of the 4 Bell states.
The first bell state can be easily implemented…
JanVdA
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18
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What applications does Grover's Search Algorithm have?
Grover's Search algorithm is usually talked about in terms of finding a marked entry in an unsorted database. This is a natural formalism that lets it be applied directly to searching for solutions to NP problems (where a good solution is easily…
DaftWullie
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18
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1 answer
Purpose of using Fidelity in Randomised Benchmarking
Often, when comparing two density matrices, $\rho$ and $\sigma$ (such as when $\rho$ is an experimental implementation of an ideal $\sigma$), the closeness of these two states is given by the quantum state fidelity $$F =…
Mithrandir24601
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18
votes
2 answers
Do multi-qubit measurements make a difference in quantum circuits?
Consider the unitary circuit model of quantum computation. If we need to generate entanglement between the input qubits with the circuit, it must have multi-qubit gates such as CNOT, as entanglement cannot increase under local operations and…
Kiro
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2 answers
How long does quantum annealing take to find the solution to a given problem?
Quantum annealing is an optimization protocol that, thanks to quantum tunneling, allows in given circumstances to maximize/minimize a given function more efficiently than classical optimization algorithms.
A crucial point of quantum annealing is the…
glS
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18
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1 answer
If quantum gates are reversible how can they possibly perform irreversible classical AND and OR operations?
Quantum gates are said to be unitary and reversible. However, classical gates can be irreversible, like the logical AND and logical OR gates. Then, how is it possible to model irreversible classical AND and OR gates using quantum gates?
Sanchayan Dutta
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18
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1 answer
Which subatomic particle does each company use in quantum computing?
Probably each company (Google, Amazon, Intel, IBM, Microsoft, D-Wave and so on) uses a mix of subatomic particles and technologies. I would like to know which particles/technologies are used by each company.
Are there specific reasons to choose a…
Felipe Rojo Amadeo
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17
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1 answer
Why are non-Clifford gates more complex than Clifford gates?
There are two groups of quantum gates - Clifford gates and non-Clifford gates.
Representatives of Clifford gates are Pauli matrices $I$, $X$, $Y$ and $Z$, Hadamard gate $H$, $S$ gate and $CNOT$ gate. Non-Clifford gate is for example $T$ gate and…
Martin Vesely
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17
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4 answers
Quantum circuits explain algorithms, why didn't classical circuits?
When explaining a quantum algorithm, many revert to 'circuit-speak' by drawing a diagram of how qubits split off into transformations and measurements, however, rarely if not never would someone explaining a classical math algorithm revert to its…
develarist
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2 answers
Can arbitrary matrices be decomposed using the Pauli basis?
Is it possible to decompose a hermitian and unitrary matrix $A$ into the sum of the Pauli matrix Kronecker products?
For example, I have a matrix 16x16 and want it to be decomposed into something like $$A…
C-Roux
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17
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2 answers
Blind quantum computing — generic structure variable selection
Background
Recently I came upon a research article entitled Experimental Demonstration of Blind Quantum Computing. Within this research article, the scientists claimed that - through the proper choice of a generic structure - a data engineer can…
Daniel Burkhart
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1 answer
Reference that explains how to read 3d topological diagrams for surface code computations
I like making diagrams to describe computations. For the surface code, an excellent tool is 3d topological diagrams. Here is an example diagram (made by me in SketchUp):
The basic idea is that white boundaries are places where Z observable chains…
Craig Gidney
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17
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1 answer
What is the Helstrom measurement?
I have been reading the paper Belief propagation decoding of quantum
channels by passing quantum messages by Joseph Renes for decoding Classical-Quantum channels and I have crossed with the concept of Helstrom Measurements.
I have some knowledge…
Josu Etxezarreta Martinez
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4 answers
How do the probabilities of each state change after a transformation of a quantum gate?
Quantum gates are represented by matrices, which represent the transformations applied to qubits (states).
Suppose we have some quantum gate which operates on $2$ qubits.
How does the quantum gate affect (not necessarily change it) the result of…
ItamarG3
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