Quantum Computing Stack Exchange
Quantum Computing Stack Exchange

Questions tagged [linear-optics]

For questions regarding the use of Linear Optics in quantum computation with photonic computers, such as those from the Psi-Quantum company, or for usage in quantum photonic experiments related to quantum information, such as the photonic characterization of quantum bits, it's manipulations and others.

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How to translate between continuous variable model and discrete model?

If I understand correctly, the discrete and continuous variable (CV) version of quantum computation are equivalent. However, the continuous aspect of the CV model makes me wonder to what extent can both models be compared. Given a discrete-gate…
Mauricio
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Why is it important to perform optical quantum computing with ONLY linear components?

The main achievement of the KLM protocol is demonstrating that quantum computing can be done with only linear optical elements, i.e., beam splitters, phase shifters, single-photon sources, and photo-detectors. I wonder why it is important to…
LearnerAL
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Any good sources to demonstrate Heisenberg uncertainty principle using polarizers?

Sakurai introduces QM using Stern Gerlach experiment. He also demonstrates HUP using the experiment. SG experiment deals with spin. However, spin is very similar to polarization. Hence, HUP should also be demonstrable using polarizers. Are there any…
Chetan Waghela
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How are two photons entangled in the Xanadu computer?

I was recently reading about how Xanadu made a scalable, room-temperature-operating quantum computer using photons as qubits (see this link). It said that in the logic gates, it entangles two photons at some point, and in the video it just looks…
Blue Herring
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Hong Mandel Effect - question on math of indistinguishability of photons

I’m working on the transformations of multi-photon states through a beam splitter, and I encountered confusion in some normalization factors . Using beam splitter transformations: $$ \hat{a}^\dagger \to t \hat{a}^\dagger - r \hat{b}^\dagger \qquad …
Kobamschitzo
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In hetero (homodyne) detection, what does it mean to operate at the quantum shot limit?

I am an electrical engineering by trade, working on the analogue part (Transmitter & Receiver) of a quantum optical communication channel. By this, I mean I have not much experience on things quantum. There are, however, some notions or concepts…
JustASneakyLittleMushroom
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Measurement Base of Fusion Gate

I am reading this article on "Fusion-based quantum computation" and they claim there about Fusion Gate type-2 that it collapses the state to 2 types of eigenstates, and returns 2 results - $ZZ$ eigenvalue and $XX$ eigenvalue (Section II, page 3): I…
Ron Cohen
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Is a Linear optical quantum computer autonomous like a Hamiltonian quantum computer?

Hamiltonian quantum computing with superconducting qubits says The appeal of a Hamiltonian approach to quantum computing is that it does not require active driving fields to enact logic. Information carriers move through gates in space, rather than…
Victory Omole
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How to entangle 2 qubits using a polarizing beam splitter?

A polarizing beam splitter splits a continuous beam of photons in 2 directions: (from here) (from here) I am curious and have a few related questions about using simple optics in quantum computing: Is splitting a light beam by polarization a…
James
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CNOT gate path interference

I have a question on paper https://doi.org/10.1038/nature02054. In this paper, the CNOT gate is realized using a beam displacer for higher stability. The figure below shows a 1:1 mapping from (a) to (b). In (a), the interference where $C_1$ meets…
유승연
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Platform to Simulate FLO of Majorana

Is there any python (other languages are also OK) library/platform/toolbox, open-source, to simulate Majorana in FLO (Fermion Linear Optics) as done in this article. I tried to look for the platform that was used in the article and did not find it.
Ron Cohen
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Combining photons at a beam splitter and states tensorization

I wonder what is the operation for 'combining' two polarized photons (one into each input arm, with perfect timing). I would consider three steps: 1.The two modes (polarization, arm) should be combined by tensor product (Left x Right states) 2.The…
Ruben Garcia
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