Questions tagged [physical-realization]

For questions about physical implementations of a quantum algorithm or other quantum information protocol. DO NOT use for questions about simulation or emulation of quantum computers, or cloud-based quantum computing services like the IBM Q Experience.

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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 ...
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How to decide which quantum device to use if a quantum algorithm is given?

I'm planning to write my master thesis in quantum computing. The subject of the thesis is to find out which attributes (properties, features) of quantum algorithms respectively their implementations (...
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Calculating power of a quantum computer — RSA

As discussed in this question, the expected security of 1024-bit RSA is 80-bits: NIST SP 800-57 §5.6.1 p.62–64 specifies a correspondence between RSA modulus size $n$ and expected security strength ...
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In D-Wave's universal quantum computer, why does the YY term have to be driven along with the linear X term?

D-Wave has a new prototype annealer that uses a Hamiltonian which, if there was enough qubits and sufficient control, would be able to simulate any universal circuit-based quantum computer with at ...
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How do we realise photonic gates?

I am interested in photonic computing, and I am curious how the gates work. I once saw a picture of a photonic CNOT gate that used just mirrors and polarizers. I have not been able to find any ...
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Are single photons necessary for this quantum autoencoder implementation?

The following diagram is from Experimental Realization of a Quantum Autoencoder: The Compression of Qutrits via Machine Learning How this setup works: What will be obtained from this set up is the ...
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Form and effect of the intrinsic Hamiltonian on the IBM machines

I want to understand the form of the intrinsic Hamiltonian of the IBM machines, such as ibmq_16_melbourne, and how this affects the data I get out when waiting ...
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Is generating usable entanglement difficult?

I'm a theorist and I assume that I can use entanglement resources for practical use freely, but is this really the case? Is generating entanglement and storing it for long enough periods of time such ...
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Are there any detailed designs for Quantum Computing hardware?

I am looking to analyze some quantum hardware designs, preferably superconducting and photonics, but I can't seem to find sources that give some detailed information. Can someone provide me designs ...
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What is the difference between a cooper pair box and a transmon qubit?

These two kinds of qubits are both classified under "charge qubits", looking for them, I always find the same circuit representation. Occasionally, I find one where there's a SQUID instead of the ...
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How to perform quantum logic gates on plasmons?

In the link provided researches utilize strong two-plasmon absorption in graphene nanoribbons to create a “square-root-of-swap”, could such a device be utilized to perform other quantum logic gates? ...
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Can one make NV centred type qubits from analogus materials in the periodic table?

Can one replace Nitrogen with Phosphorus and Carbon with Silicon and so on? What would be the conditions that would preclude such a realisation? Are there any implemenations so far?
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Does self-induced collapse limit the size of a quantum computer?

This question is related to this question, but I'm specifically interested in self-induced collapse. Suppose that the size of a quantum system alone somehow leads to a projection of the state (a "...
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What are the most popular QND measurement implementations used in photonic quantum computers?

What components are used in order to perform QND measurement in photonic quantum computers?
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Crosstalk error of simultaneous cnots

We can use simultaneous randomized benchmarking (SRB) to quantify the crosstalk impact of simultaneous CNOTs. The crosstalk error is caused by many reasons, for example, the always-on ZZ interaction, ...
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How to do the counting when computing the fault tolerant threshold of quantum codes?

Here, I want to ask a basic question about how to compute the fault tolerance threshold of quantum codes. As I know, maybe, the most usual way is to do some simulations. Howvever, I am more intersted ...
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What are Sideband Pulses

I see sideband pulses used all over the place when looking up implementation techniques especially in Trapped Ion QC. Is there a layman's explanation of what they actually are? I understand what they ...
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What are the practical limitations of complementing quantum computations with memristors?

Considering the current state of research into quantum memristors, and the advantages/disadvantages of quantum and memristor driven computing architectures: Quantum Memristors Quantum Memristor ...
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Long range two qubit gates in superconducting qubits

In superconducting qubits, all the method that I have seen until now are based on short range interaction. For example you have two qubits to process information around a middle qubit that is ...
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Where does the energy go in a Power Rabi experiment with superconducting circuits?

When performing a Power-Rabi experiment, e.g in superconducting circuits, we are playing a pulse to a qubit and then reading out its state by playing another pulse to a dispersively-coupled readout ...
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Why does non-locality and the particle-hole symmetry not contradict each other?

Currently, I'm learning about topological quantum computers. In one of the explained techniques, cooper pairs in superconductors are considered, where a cooper pair with a hole form a Majorana bound ...
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How can I achieve single-qubit $T$ operation using spin resonance?

We know that $T$ gate is as follows $T=\left(\begin{array}{cc}1 & 0 \\ 0 & e^{i \pi / 4}\end{array}\right)$ And on the other resultant spin-resonance hamiltonian is $\frac{H}{\hbar}=\frac{1}{2}...
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How qubit phase is build in real hardware?

How qubit phase is build in real hardware? On IBM Quantum, D-Wave, etc?
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What are the general hardware components of a universal quantum gate computer?

Although the architecture of a quantum computer depends on the implemented qubit system, I still wonder what the general structure of hardware parts would be. Evidently, a quantum computer isn't ...
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Which type of quantum computer is explained by spin-boson Hamiltonian?

In a review paper of decoherence-free subspace(DFS) [1], they consider the spin-boson Hamiltonian and they write the system of qubits could be the spins of N electrons trapped in the periodic ...