Questions tagged [logical-observables]

5 questions
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How do the logical operators change from round to round in the CSS Floquet code?

In the hexagonal CSS Floquet code, we measure checks in rounds that alternate X and Z and colours: RX, GZ, BX, RZ, GX, BZ. I.e., for RX, we are measuring all the red edges in X. What does the logical (let's say, X) operator look like at each…
3
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1 answer

How does one identify Pauli logicals in a hyperbolic surface code?

I understand how the Pauli X and Z logicals on the planar surface code work - they are stringlike operators between either the rough boundaries (in case of the Z logical) or between smooth boundaries (for X logical). I choose these boundaries in…
2
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1 answer

How to initialize the Surface Code in the $\pm Y_L$ State, perform logical $Y$-basis measurement, and $S$ logical gate clarification?

I am trying to learn more about logical state initialization, logical operators, and measurement for the surface code. I am having some trouble understanding the nitty-gritty details of the logical $\pm Y_L$ initialization and logical $Y$…
1
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0 answers

Measuring a single-qubit PauliZ using Qiskit's EstimatorQNN

I am currently working with the EstimatorQNN from Qiskit to construct a Quantum Neural Network using a custom Parametrized Quantum Circuit. But I want to change the observables in the EstimatorQNN. By default, the observable returns the product of…
1
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1 answer

Y observable from surface code in Stim

I understand that, in the surface code, it is generally harder to measure $Y_L$ compared to $X_L$ or $Z_L$, and code deformations are generally required. However, is there an easier way to calculate this information for a Stim surface code circuit,…
jchadwick
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