Quantum Computing Stack Exchange
Quantum Computing Stack Exchange

Questions tagged [photonics]

It is the branch of physics and engineering concerned with the properties and transmission of photons. Use this tag for those questions about photonics which are relevant to quantum computing.

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Is it possible to "calculate" the absolute value of a permanent using Boson Sampling?

In boson sampling, if we start with 1 photon in each of the first $M$ modes of an interferometer, the probability of detecting 1 photon in each output mode is: $|\textrm{Perm}(A)|^2$, where the columns and rows of $A$ are the first $M$ columns of…
user1271772 No more free time
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Do any educational quantum computing toys or devices exist?

Question inspired by this article from IEEE Spectrum on blocks containing different polarization filters for use in classrooms, and my previous question on representing the three-polarizing-filter experiment in quantum computing terms. Here I want…
ahelwer
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What components are needed to realize a photonic CNOT gate?

In Realization of a photonic CNOT gate sufficient for quantum computation FIG. 1 there is a "scheme to obtain a photonic realization of a CNOT gate with two independent qubits." What components are needed to realize a photonic CNOT gate?
user820789
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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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What are the main obstacles to overcome to build silicon-photonic quantum computers?

In superconducting quantum computers, we use mostly superconducting qubits or trapped ions. However, those systems are quite large because their environment either requires near absolute zero temperature (for superconducting to happen), or vacuum…
Aleksandar Kostovic
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Analyzing the three-polarizing-filter experiment as a quantum circuit

In the three-polarizing-filter experiment, two orthogonal polarizing filters block all light but then allow some amount when a third polarizing filter is placed oriented at a 45 degree angle between them. Can we analyze this experiment through terms…
ahelwer
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Is Gaussian boson sampling (used for showing quantum advantage) a subcategory of the continuous variable approach?

I read about the photonic QC Jiŭzhāng that showed quantum advantage by Gaussian boson sampling. I read that boson sampling itself is a sub-universal technique of QC (where they use single-photon states as input states). In the paper, the scientists…
ile2N
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What are some good resources for learning about photonic qubits?

I am interested in resources that would allow me to learn about the physics behind optical quantum computation, and specifically, the physical properties of photonic qubits. I have some good resources on quantum optics, but is there anything more…
Jack Ceroni
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Is 216 qumodes photonic quantum processor equivalent to 216 qubits superconducting quantum processor, in terms of computational power?

Xanadu just launched borealis, 216 qumodes photonic quantum computer, this week. https://xanadu.ai/blog/beating-classical-computers-with-Borealis Its number of qubits is very interesting because it has twice the number of qubits of IBM Quantum…
Natchapol Patamawisut
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Does a photonic quantum computer control a single photon?

Does a photonic quantum computer control a single photon and use it to represent a single qubit? I think ion trapped quantum computers use a single ion to represent a qubit. I would like to know how a photonic quantum computer represents each qubit.
david
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Optical quantum computers VS Superconducting quantum computers VS Electron-spin quantum computers

One of the main problems of superconducting quantum computers is that it is necessary to maintain a very low temperature (near absolute zero). Such cooling is very expensive and complex. Why, then, are Intel, IBM, and many other corporations…
alexhak
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Physical Interpretation of Pauli Matrices as Polarization Check

We know that the Pauli matrices are: $$\sigma_x = \begin{bmatrix}0 & 1 \\ 1 & 0\end{bmatrix}, \sigma_y = \begin{bmatrix}0 & -i \\ i & 0\end{bmatrix}, \sigma_z = \begin{bmatrix}1 & 0 \\ 0 & -1\end{bmatrix}$$ I was wondering what would these matrices…
QuestionEverything
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Multi-photon states in photonic quantum computing?

Within photonic quantum computing, one of the ways to represent information is the dual-rail representation of single-photon states ($c_0|01\rangle \ + \ c_1|10\rangle$). Is it possible to utilize multi-photon states (for example, two optical…
Jack Ceroni
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How is the polarization of a photon able to hold quantum information?

It is my understanding that light, and its polarization, is used to transfer information in quantum computers, but how can the information encoded in say, an electron also be stored in light? I understand that the spin of an electron or other…
rotowhirl
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What does negative probability represent?

"Negative energies and probabilities should not be considered as nonsense. They are well-defined concepts mathematically, like a negative of money." -Paul Dirac The abstract from Photon-phonon-photon transfer in optomechanics states: the Wigner…
user820789
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