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Questions tagged [lattice-surgery]

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Open-source code for Lattice Surgery in STIM

I'm looking for open-source code that implements lattice surgery merging and splitting between two rotated surface code logical qubits in STIM (for d=3 or above). Whilst there are some excellent ...
ebit157's user avatar
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error correction after lattice surgery for merging

Imagine you have merged two surface codes with lattice surgery by measuring all the stabilizers and treating both surface codes as one surface code, then are we doing error correction before or after ...
Shahrooz Pooryousef's user avatar
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Confusion about lattice-surgery operation

According to https://arxiv.org/abs/1111.4022, to perform a logical CNOT using lattice surgery, three patches of surface codes are needed and nearest neighbour operations are performed. However, I ...
AndyLiuin's user avatar
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Kraus decomposition of merging in lattice surgery

I am reading about lattice surgery from this paper. I am interested in the merge operation which takes 2 qubits to 1 qubit. I want to understand the logical-level Kraus operation that the merge does. ...
qubit's user avatar
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State injection in a surface code

I am reading this paper on lattice surgery by Dominic Horsman et al, and am struggling to understand a simple method they put forward in their Figure 8(a)(b)(c) to inject an arbitrary state into a ...
quantumctrl's user avatar
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Fault tolerance of turning off a stabilizer measurement for later rounds of error correction?

Suppose during a smooth lattice merge operation, I perform one round of error correction, treating the two code patches as one single lattice that stretches across the intermediate qubits. Then, one ...
usermm's user avatar
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2 votes
1 answer
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High logical error rates when implementing Lattice Surgery with Stim

I'm facing a strange issue with the logical error rate after implementing Lattice Surgery in Stim. For $d=3$ (I have some custom error annotations in the circuit), ...
control freak's user avatar
1 vote
1 answer
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How does one perform an $S$ gate on a surface code patch using lattice surgery?

I'm attempting to understand how to perform universal quantum computation via lattice surgery. I'm struggling to find any resources for $S$ gates with lattice surgery. I would greatly appreciate an ...
Palash Goiporia's user avatar
3 votes
1 answer
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Can you produce Non-Clifford gates via Lattice Surgery?

Is there any theorem stating that lattice merge/split operations (or perhaps more generally, so-called gauge-fixing) cannot produce a non-Clifford gate that can complete the universal gateset for the ...
usermm's user avatar
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1 vote
1 answer
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Lattice surgery and real-time decoding

This question pertains to the real-time classical processing required while running the surface code. Consider two logical patches $P$, $P'$. Let's assume that after $d$ rounds, a ...
control freak's user avatar
1 vote
0 answers
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What are the differences between code deformation, code conversion, code switching and gauge fixing?

From my understanding so far: Code switching is essentially just a fault-tolerant mapping between two codes. It's called code conversion if it's gradational, i.e. changes to stabilizer generators are ...
tomek's user avatar
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Number of logical cycles to implement $R_Z(\theta)$ gates in lattice surgery: why isn't it the number of layers $\times$ the $T$-count in $R_Z$?

Let's assume I want to implement a rotation $R_Z(\theta)$ for a lattice-surgery based computation, for $\theta$ being an arbitrary angle (i.e. the gate is not necessarily Clifford nor a $T$-gate). It ...
Marco Fellous-Asiani's user avatar
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Litinsky's fast block scheme: should the tile count also include the number of **purified** magic-states

I was looking at the assumptions behind the Microsoft Azure resource estimator, which is mostly built on Litinsky's paper. Calling $Q_{\text{Alg}}$ the number of logical qubits required by the end-...
Marco Fellous-Asiani's user avatar
2 votes
0 answers
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lattice surgery in state picture

I was following Surface code quantum computing by lattice surgery. A few questions about this paper have been asked in this forum, but I believe my question is new. The main text took a 'state picture'...
quTANum's user avatar
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When do we need to decode live the syndromes? Various examples to understand

I would like to precisely understand why we need to decode syndrome "live" when we want to perform $T$ gates. For this reason I consider different scenario (some are fictive but helpful to ...
Marco Fellous-Asiani's user avatar
2 votes
1 answer
83 views

15-to-1 distillation protocol in lattice surgery: doesn't the potential rejection of the level-1 magic states makes it last longer than $15$ timestep?

Overview of my question I am following Litinsky's paper, and I would like to better understand how the duration of the level-2 15-to-1 distillation protocol is being estimated. Litinsky's says that it ...
Marco Fellous-Asiani's user avatar
6 votes
1 answer
241 views

Getting intuition on the state-injection relations for the generalized $\exp(-iP \pi/8)$ $T$-gates (ideally using ZX calculus)

In Litinsky's paper, there are many circuits relations, like the one below. The left handside represents the "rotation" $\exp(-i P \phi)$ with $\phi=\pi/8$ with similar definitions for the ...
Marco Fellous-Asiani's user avatar
2 votes
1 answer
136 views

Lattice Surgery: how does lattice merging act on the physical qubits?

I am reading 2013, Horsman D. et al. - Surface code quantum computing by lattice surgery. I have been trying to understand how the outcome of rough lattice merging, which is discussed using both ...
Giovanni Canossa's user avatar
1 vote
1 answer
125 views

Using Pymatching to decode lattice surgery process

I want to simulate the error correction procedure for a CNOT gate on surface code and RHG cube, made by the lattice surgery process of "merge and split". In this case, the code has an H-...
Yaron Jarach's user avatar