# All Questions

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### How to prepare a random 1-qubit superposition for data encoding

Let's assume we have a normalized data vector $\vec{x}= [x_1,x_2]$. How can I prepare a state $$|\psi\rangle = x_1|0\rangle+x_2|1\rangle$$ for any $\vec{x}$. I know that this state is in general not ...
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### Measurement probability of a state from three hilbert spaces

I'm curious how to find the probability measurement of a state when one qubit is measured. For example this state: $|\gamma\rangle = \frac{1}{\sqrt{2}}(| 010 \rangle + | 101 \rangle )$ Assuming these ...
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### Grover's oracle

Grover's algorithm works by iteration of the operator $$G:=U_S^\perp U_f=H^{\otimes n}U_0^\perp H^{\otimes n}.$$ I know how to write down the matrix for $U_S^\perp$ (the inversion about the average ...
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### QISKit not installing in PyCharm

I am attempting to setup a PyCharm project to study and work through the QISKit textbook. However I seem to be running into a propblem seting it up. I have setup a python enviroment via anaconda (...
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### Measure qubit $q_0$ in some basis that remotely prepare in qubit $q_1$

I constructed a circuit that characterized the creation of a Bell state. Now I want to measure qubit $q_0$ in some basis depending on the state $|\psi\rangle$ that I want to remotely prepare in qubit ...
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### Is there any quantum gate that can change quantum hardware topology(architecture)?

I read about this paper Hardware-aware Heuristic for the Qubit Mapping problem in the NISQ Era. I wonder there is the only SWAP gate that can change the quantum hardware topology. Is there any gates ...
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### Is it better to initialize quantum circuits in Qiskit by passing QuantumRegister and ClassicalRegister objects?

From the perspective of building quantum computation software based on Qiskit, which approach to defining quantum circuits is more robust? ...
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### What is the general method for creating real gate sequences from mathematical algorithms?

Background I have been doing research on quantum computing on my own for over a year now and I feel like I may have missed a fundamental step. I have no idea how to take a mathematical algorithm and ...
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### Implementing a SwapTest for samples with large numbers of features

I am trying to calculate the distance between sets of vectors. To do this I can create a SwapTest circuit (described here on page 34) and encode a feature vector with a U3 gate, then apply H and CSWAP ...
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### Symmetric Universal Quantum Cloning Machine (UQCM) N --> M for unknown states

Does it exist a schematic diagram of the quantum circuit implementing the symmetric UQCM N--> M for unknown states? If yes, does anyone know a Qiskit implementation of it?
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### How to convert discrete quantum circuits to their continuous variable equivalents?

With a full set of either CV, or qubit gates, you should be able to implement a universal circuit. I am wondering how to "convert" one circuit to another. If I have a circuit with a U3 gate, ...
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### How can we construct a control-control y-rotation (CCRy) gate in Qiskit?

Qiskit has a CRy gate, however I couldn't find a CCRy (double control Ry) gate implementation. How can we construct the CCRy circuit given below in Qiskit without any ancillary qubits? Edit: A quick ...
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### How to implement the swap test with the help of qiskit?

It's creating a real confusion for me especially the parameterized circuit which I have to create. Can anybody please solve this for me? I want to create this circuit.
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### In quantum adiabatic simulation, is the $s$ in $(1-\frac{s}{T})H_{in}+\frac{s}{T} H_{cl}$ related to the $t$ in $e^{-iHt}$?

I just want to do a whole adiabatic calculation on quantum circuit. To prepare two Hamiltonian of $H_{initial}$ and $H_{classical}$ and solve $H_{classical}$ using adiabatic calc like quantum ...
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### How can one argue that the $S$-gate is Clifford while $T$-gate is not?

How can one argue that $S$-gate is Clifford while $T$-gate is not?
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### How significant is achieving electronic transport in a single qubit at room temperature?

This is a follow-up to a previous question I asked: How promising is the possibility of carbon-based qubits to make a qubit that’s stable at room temperature? I am trying to assess the significance of ...
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### What is a good program to practice using a quantum algorithm? Should I use Cirq or Qiskit?

I am starting to learn about Quantum Computers and Quantum Algorithms. I also started reading about Qiskit and Cirq. I really like learning about them and hopefully I can be a Software Engineer with ...
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### How to implement $\sqrt{iSWAP}$ in Qiskit

I want to implement the $\sqrt{iSWAP}$ operator using simple operations in Qiskit such as it is done for the $iSWAP$ here or $\sqrt{SWAP}$ gate here. How can I do this? If possible I would like to ...
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### unable to install qiskit-aqua[cvx]…While installing, i am getting the below error. If anyone can suggest

I am unable to install qiskit-aqua[cvx]...While installing, i am getting the below error. If anyone can suggest. I have pasted the error snapshot below
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### What does “large-scale universal quantum computation” mean?

I was reading this lecture notes by Sevag Gharibian. He mentioned the following statement: Large-scale universal quantum computer can be built. I do understand what quantum computer is, but I don't ...
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### Qiskit textbook - exercise 2.2 - why doesn't the correct answer give the same statevector?

In the Qiskit textbook, I'm stuck on one of the exercises in section 2.2. The question is: Write the state: as two separate qubits. The answer has already been covered in this question here, and is ...
### How many real numbers are required to describe density matrix for $n$ qubits?
(All of these coming from the topic of simulation of quantum systems) A density matrix $\rho$ Which describe state of $n$ qubits will have $2^{n} \times 2^{n}$ size. We have couple of conditions like ...