To my knowledge, in a Quantum Computer it is possible to obtain any Bell state by applying a Hadamard gate onto a qubit state $|x\rangle$ followed by a CNOT gate onto some target qubit state $|y\rangle$. This procedure can then give rise to a maximally entagled state $|x=0\rangle |y=1\rangle\rightarrow \frac{|01\rangle +|10\rangle}{\sqrt{2}}$. My question is whether this procedure presents some practical problems when it comes to experimentally actuate it. If so what are these difficulties? Is this a reliable way to produce a maximally entangled state? Otherwise, what problematics had to be faced in order to make this method reliable?
1 Answer
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Generally speaking, the practical limitations of quantum computing are in the form of noise, and quantum decoherence, both of which occur due to interaction with the environment.
Noise in quantum computers occurs as a result of the interaction of electromagnetic fields with the qubit. It leads to some randomness in the number of photons being analysed by the detector.
As for quantum decoherence, the interaction with the environment causes a change the quantum states of the qubits, thus causing information to be altered and ultimately lost.
