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Questions tagged [arithmetic]

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Highly-efficient $n(n+1)$?

Appendix G of this paper provides a highly-efficient way of squaring integer numbers. (LMK if anything more advanced is already available.) I'm wondering if this approach can be easily modified to ...
mavzolej's user avatar
  • 1,951
1 vote
0 answers
93 views

How can I initialize a classic register in qiskit?

is there a way to initialize a classic register in qiskit? I will go quickly through my problem and then suggest one solution but I am not satisfied with that and ask if there is another solution. ...
Qubii's user avatar
  • 191
3 votes
1 answer
42 views

On unitary matrix form suggested in the Elementary gates paper

In the Elementary gates for quantum computation paper by Barenco et al authors start their proofs by defining a generic form of 2x2 unitary matrix of $\mathbb{C}$ as follows: Can you help me with the ...
Grwlf's user avatar
  • 133
0 votes
1 answer
50 views

Qiskit: RGQFTMultiplier is giving wrong answers for 28 bits number multiplication with MPS simulator

I am using RGQFTMultiplier for multiplying two unsigned integers. Starting from simpler example of 2 qbits input, I reached 24 and all worked fine. I am using MPS as backend and my RAM is 32. However ...
aneela's user avatar
  • 233
2 votes
1 answer
44 views

Comparing qubit values in pairs of qubits

For $2N$ qubits $\{i_1,j_1\ldots i_N,j_N\}$ I would like to have a circuit changing the value of an ancillary register from $0$ to $1$ if $i_1=j_1$ AND $i_2=j_2$ AND ... AND $i_N=j_N$. One way to ...
mavzolej's user avatar
  • 1,951
1 vote
2 answers
140 views

Problem adding two numbers in a quantum computer with Drapper's algorithm

I would like to add numbers. In this simple example a = 1 and b = 1. The circuit I created looks like this: We have two registers a and b. Both have a size of 3 qubits. I'm using Big Endian notation, ...
Oli's user avatar
  • 57
0 votes
1 answer
208 views

Why a Fourier Adder Gives Multiple Faulty Results?

I followed this tutorial and wrote a code that implements the following circuit: By writing the following code: ...
Himanshu Bansal's user avatar
3 votes
3 answers
266 views

Is it possible to implement an in-place multiplication quantum circuit?

How can a reversible multiplication quantum circuit be implemented? By "reversible" I mean one that performs a *= b on the inputs a and b of the ...
yasuhito's user avatar
2 votes
1 answer
138 views

Oracle for amplitude addition

Assume one is given two oracle circuits providing access to matrices $A_{ij}$ and $B_{ij}$ as follows (see eq. (6.2) here): \begin{equation} O_A |0\rangle|i\rangle|j\rangle=\left(A_{ij}|0\rangle+\sqrt{...
mavzolej's user avatar
  • 1,951
2 votes
1 answer
62 views

How can one sort two registers without leaving an entangled ancilla behind used for comparison?

If we have an state $\alpha|abc\rangle + \beta|bad\rangle$, and we know that $a<b$, how can we obtain state $\alpha|abc\rangle + \beta|abd\rangle$ without entangled ancillas, if we don't know $c$ ...
Pablo's user avatar
  • 511
3 votes
1 answer
103 views

How to verify a matrix-vector product with Grover search?

I am looking at the Ambainis et al. method of verifying whether $AB = C$ in $O(n^{7/4})$ queries, as described in Buhrman and Špalek. They have the following sentence: verify the matrix-vector ...
416E64726577's user avatar
2 votes
1 answer
96 views

Formulate Controlled-Not as mapping (including modulo-2 addition)

We often see that the controlled-not gate is written as $CNOT |x y \rangle = |x\rangle |x \oplus y\rangle$. Now, would it be possible to further expand this to get a general equation? $$(\alpha_0 |0\...
Fabian's user avatar
  • 35
8 votes
4 answers
616 views

Computing $e^x$ on a quantum computer

Does anyone know how to make a quantum circuit to compute exponentials where the exponent can be a fraction? To be more precise, I'm looking for a fixed point quantum arithmetic circuit that does the ...
sheesymcdeezy's user avatar