# Tag Info

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Generally, a simulator does not have to do any decomposition of gates to hardware-level specifics. Simulators only follow a mathematical model of a gate (described by matrix). Since each algorithm can be described by a matrix, whole simulation can be expressed as $|\psi_1\rangle = U |\psi_0\rangle$, where $|\psi_0\rangle$ is initial state of a quantum ...

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There are several separate questions entangled here. Using Q# with Python as the host language is similar to using Q# with C# or another classical host language: it allows you to run Q# code and do necessary classical processing (for example, preparing the data or analyze the results). The Q# code invoked from the classical host language has to be written ...

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If your circuit is a component of a larger circuit then global phase may matter. See relevant discussions in https://github.com/Qiskit/qiskit-aer/issues/353 and https://github.com/Qiskit/qiskit-terra/issues/3083.

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Your target state and the state that you get only differ by a total factor of $-1$. In other words, if $|\psi\rangle$ is the state that you get and $|\psi_{t}\rangle$ is the target state, we have: $$|\psi\rangle = (-1)\times|\psi_{t}\rangle = -|\psi_{t}\rangle.$$ Such a overall factor is known as a global phase. People think of it as a phase, because we ...

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How then, would one be able to simulate say CHSH, which produces fundamentally quantum probabilities that cannot be explained locally/classically? Am I misinterpreting the meaning of simulate? Quantum phenomena cannot be "explained classically" only when locality is taken into consideration. In other words, classical phenomena cannot reproduce (some types ...

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There are two definitions of simulation that are commonly used in this context. We consider a quantum computation to be: 1. loading an input 2. performing some processing 3. doing a measurement This defines a distribution on possible measurement outcomes for each input. Weak Simulation would be a classical randomised algorithm that could sample from these ...

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Here's how you can use statevector_simulator to get an exact answer: import numpy as np from qiskit import QuantumCircuit, execute, Aer from qiskit.visualization import plot_histogram # Use Aer's statevector_simulator simulator = Aer.get_backend("statevector_simulator") # Create a Quantum Circuit acting on the q register circuit = QuantumCircuit(2, 2) # ...

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In simulation, it is normally not needed to perform the process of decomposition - so your perspective is right, in principle. Of course, it can be actually useful to perform the decomposition and synthesis, for various reasons, including but not limited to: The gate decomposition algorithm itself needs to be simulated (Rather than the algorithm/...

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Why bother with an approximate solution when you can get an exact solution? The reason to have an 'approximate' simulation rather than an exact simulation (and result) is that it more closely resembles our understanding and interaction with a real quantum computer. In a real quantum computer, the state of the qubits before measurement is indeed the exact ...

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He has basically described how to build the Cirac-Zoller quantum computer. In the most simple approach the qubit states are electronic states of the trapped ions. Two qubit gates are possible thanks to the coupling of the qubit states to the vibrational modes of the trap -- this is cool as in superconducting architectures the two qubits that are far apart ...

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All previous answers are true. I would like to contribute with a serious question and a comment. Would it make sense to build a quantum computer in your house? They are and will be hard to maintain. In my opinion, having them in the cloud is and will be the best solution. Beecause of economy of scale, the cost of a home-made quantum computer will be ...

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It's actually an interesting question. And the previous answers ("strictly speaking, you can't," "you can simulate quantum computers," and "photonics-based processing holds some promise") are all true. According to a pioneer in photonics computing we won't see real quantum computing until around 2035. I've not yet seen anything to justify thinking to the ...

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Note that while you probably can't build a quantum computer at home, you can simulate one with a classical computer, at the cost of merely an exponential slowdown. There's a rather long list of available software at https://www.quantiki.org/wiki/list-qc-simulators.

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With current technology, there's not much of a chance to build a true quantum computer, but you may be able to build some interesting quantum circuits with a fairly sizable (but still on the scale of "self-funded" for the ordinary person) budget, using the optical photon model. For instance, one could use the linear optical quantum computing model. Using ...

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A serious answer: you pretty much can't. It's not that you in particular can't, it's that no one can. Huge companies pour in huge amounts of money to try and make a proof-of-concept quantum computer (there is actually no 'proper' quantum computer yet). A slightly less serious answer: some odd $10-100$ Million would get you started I would say. It all ...

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