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# Questions tagged [bell-experiment]

For questions on Bell test experiments or Bell's inequality experiments, including but not limited to the CHSH and CH74.

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### Why divide $\theta$ by 2 when doing the Bell's Inequality Experiment?

I understood the CHSH game correlations by watching Prof. Vazirani's video. I also understood that the correlation between two measures taken from different basis are related by the cosine of the ...
1 vote
73 views

### Semi-Definite Program to maximise $P(X)$ with a fixed CHSH value

This question should be theoretically simple, yet I'm struggling as something may be incorrect about my code. I am trying to plot a graph of the maximum probability ($P(x)$) of a given system against ...
1 vote
118 views

### How can I simulate EPR and Bell’s inequalities in qiskit?

According to Bernard Zygelman "A First Introduction to Quantum Computing and Information", I can compute the $QS|f\rangle$ with $|f\rangle = \frac{1}{\sqrt{2}} (|00\rangle -|11\rangle)$, ...
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### Output of Bell State Measurement

I was trying to see the output of Bell State Measurement in IBM Quantum Experience but in the simulation down the circuit in the histogram, it showed me that the possible qubit will be $|00\rangle$ ...
800 views

### Difference between Bell's inequality and CHSH

In this section of the Scholarpedia article on Bell's theorem, the first paragraph comments that Bell's original inequality is not ideal for experimental verification because it requires perfect anti-...
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1 vote
232 views

### Where does $xy = a + b \pmod 2$ come from in the context of CHSH inequalities?

I have been looking into the great! video lecture of "CSHS Inequality" by Prof. Umesh V. Vazirani. There are a few things I have to clarify, hope someone will answer me. Suppose Alice and ...
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428 views

### Is this a Bell test?

Inspired by this article which uses a $|+\rangle$ state as a control for a $CSWAP$, I realised you can conditionally measure a qubit by (maybe) swapping it with an empty ancilla, measuring it and (...
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94 views

### What is the analysis of the Bell Inequality protocol in Cirq's 'examples'?

This question is taken from https://github.com/quantumlib/Cirq/issues/3032. The "standard" protocol measures Alice's and Bob's qubits in different bases, while the one in Cirq measures in ...
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338 views

### Problem about entanglement swapping

I have been learning about the concept of entanglement swapping and found an equation mentioned in the textbook, Mathematics Of Quantum Computing: An Introduction written by Wolfgang Scherer. At ...
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2k views

### How to prepare an arbitrary two-qubit state?

I know that to prepare a Bell state say $|\phi^+\rangle$, we need to initial state $|0\rangle,|0\rangle$ and then perform a Hadamard on the first and then use it as control to do a NOT gate on the ...
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### Bell State 11 not working for parity curve

I am currently writing a script to automate the creation of parity curves for a 2 qubit bell state and then calculate fidelity and proving entanglement from that (inspired by this paper). It was going ...
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303 views

### Simultaneous eigenstate of commuting observables and their tensor product

So this is about something from Preskill's notes on Quantum Computation and Information, Chapter 4, page 3. Imagine we have a maximally entangled state (Bell state). We can identify the Bell state by ...
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### Why is $P(1,2)_{\text{same}} = \frac{1}{4}$ and not $\frac{1}{2}$ in Preskill's Bell experiment?

Context: Three coins on the table. Each is either heads or tails. You can uncover any one of the three coins, revealing whether it is heads or tails but then you choose two the other two coins ...
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141 views

### Determining whether $P(ab|xy)$ factorizes in Bell experiments

Continuing from my previous (1, 2) questions on Brunner et al.'s paper on Bell nonlocality. Again, we have the following standard Bell experiment setup: where independent inputs $x,y \in \{0, 1\}$ ...
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241 views

### Definition of locality in Bell experiments

Continuing from my previous question on Brunner et al.'s paper; so given a standard Bell experimental setup: where independent inputs $x,y \in \{0, 1\}$ decide the measurement performed by Alice &...
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151 views

### References examining Bell inequality violations at large distances

Could anyone point to some references examining Bell inequality violations at large distances please? I see many times, in pop science articles and research literature alike, that the quantum ...
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