# Questions tagged [grovers-algorithm]

Grover's search algorithm is an algorithm that can perform a search in the order of square root of the input size. This is a provable speed up over the best classical algorithm, which requires a time of order N to perform a search.

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### Oracle with multiple solutions, Grover's Algorithm- Qiskit

Using qiskit, I want to build an oracle with multiple solutions. I am planning to use 10qubits. I don't know if i'm doing it right but where it goes: ...
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### Trying to understand Grover's Algorithm

I'd like to start with saying sorry if my question makes no sense as I'm a physics student, but only in third year. I've discovered Grover's algorithm, but what I'm not sure of is if it could be used ...
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### What is the circuit for grover's algorithm if N is not a power of 2?

From the literature it seems that grover's algorithm works if $N$ is not a power of $2$. For instance, https://en.wikipedia.org/wiki/Grover%27s_algorithm and https://arxiv.org/abs/quant-ph/0005055 I ...
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### Can quantum search be performed without phase estimation?

In the quantum search algorithm with a known number of answers $M$ out of a search space of size $N$, it seems that the algorithm works pretty well (though not with pinpoint accuracy) for a fairly ...
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### Applying Hadamard gate to $\sqrt{3/4}|0\rangle + \sqrt{1/4}|1\rangle$

[I am just transferring this from Stack Overflow. It might need editing.] ———— [The reader can skip to “It all sounds fine…”, before the spreadsheet representation.] I am trying to figure out quantum ...
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### Negative Probability — Reality vs Description [closed]

I understand that quantum physics supports the concept that the probability of a qubit collapsing into (say) 1, can be negative or positive… and that quantum computing uses this as a feature, adding ...
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### BHT algorithm implementation

Summary of Method Amplitude Amplification Summary The BHT algorithm uses amplitude amplification, a nice generalisation of Grover's algorithm, where there is a subset $G\subset X$ of good elements in ...
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### How does the amplitude amplification in Grover's algorithm work?

As the question says - how does the amplitude amplification in Grover's algorithm work? I am fine with adding the negative phase on the winning state, but how does one generate the diffuser to ...
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### How can one evaluation of $U_f$ in Grover's algorithm use only one query of $f$?

I am very much new to quantum computation and do not have a background in quantum mechanics, which I believe is at the root of my confusion around Grover's algorithm. Suppose that we have a search ...
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### Does Qiskit Statevector has actual speed up for Grover Search?

From Qiskit document, the Statevector can be used to specify the oracle of Grover Search. After seeing the source code of the operators, it seems a statevector is converted to a rank-1 projector ...
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### Is there recent research on experimental implementations of Grover's algorithm with more than 5 qubits?

I could only find experimental work on Grover's algorithm upto 5 qubits here. Is there any more recent research for larger database sizes where Grover's algorithm is employed? Is there any known ...
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### Implementing EQP Simon's (removing trivial solution)

I have been studying Brassard and Hoyer's paper, An Exact Quantum Polynomial-Time Algorithm for Simon's Problem (https://arxiv.org/abs/quant-ph/9704027). I have successfully implemented Section 4.1 ...
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### Can Grover's algorithm be applied to differential equation solving?

As I understand Grover's algorithm, given the output of a black-box function, can be used to find the corresponding input (or set of inputs if the function is not one-to-one). It is therefore ...
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### issues running a 32 qubit grover's algorithm

I have a 32 qubit grover's algoritm however whenever I run it on the simulator that IBM offers it always ouputs a probability of 1 on every single result. Is there a way to run circuits larger then 32 ...
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### What is the point of Grover's algorithm, really?

This is a question desguised as a rant. There is a similar question here, What's the point of Grover's algorithm if we have to search the list of elements to build the oracle?, but the answers have ...
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### Can I use Grover's algorithm on overlapping sets of qubits?

Let's say I have 3 qubits: $q_1,q_2,q_3$. I want to apply Grover's algorithm on q1,q2, such that q1,q2 $\neq$ 10 and do the same for q2,q3, so that q2,q3 $\neq$ 11. The final possible combinations of ...
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### Can I use Grover's algorithm for a function that has multiple arguments which satisfy it?

Let's say we have a function $f(x)$, where $f(011) = 1$, and $f(111) = 1$. Can I still use Grover's algorithm with this function, and receive the result of either $011$, or $111$?
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### Does Grover's algorithm always give the correct answer with 100% certainty for two-qubit states?

In the Qiskit tutorial on Grover's algorithm it is stated that with a 2 qubit algorithm the chance of measuring the "right" state is already 100%. But I thought that the algorithm would ...
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### Is there an issue preventing people from scaling Grover's algorithm to larger numbers of qubits?

IBM's quantum experience offers computing up to 15 qubits however through my search of current literature the largest implementation for the algorithm has been with 4 qubits. Is there an issue, ...
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### Q-means, QRAM and how it helps algorithmic speedup

I am trying to understand how QRAM will help improve algorithm performance. I am reading a paper on Q-means classification, but I have noticed that some other algorithms (Grovers) seem to have a ...
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### How is the Grover iteration realized in an actual quantum circuit?

The number of the Grover's diffuser iterations is proportional to square root of the amount of input data, but how is this realized when building a real quantum circuit? Is it simply by concatenating ...
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### In Grover's algorithm, how does the function know what element is to be searched for? [duplicate]

In grover's algorithm the oracle gives the output 1 if the element we want is there, my question is, how does the function know what element is to be searched for or how do you put in the element you ...