Esha Swaroop
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eshaspark.bsky.social
Esha Swaroop
@eshaspark.bsky.social
PhD student working in quantum error-correction at IQC & Perimeter Institute, Waterloo.
some visuals to complement 3 recent papers on logical gate schemes for arbitrary quantum LDPC codes. :)
March 10, 2025 at 5:09 AM
Reposted by Esha Swaroop
Thiago put together a nice plot summarizing how this result fits into other results about bounds of time/space overhead vs locality. In terms of this plot, the paper's goal was to put a circle in the O(1) column, but not in the "all" row.
February 25, 2025 at 9:24 AM
there must be some trickle down effect onto efficacy of two stages?
February 6, 2025 at 3:51 PM
ah, P_{1,17} is ~e^14 so it's still cubic suppression, but the qutrit code offers much better constants.

Trading hundreds of qubits for just 20 qutrits isn't a big ask in terms of temporarily switching dimension of the system either.
February 6, 2025 at 3:40 AM
where is this from?
if one throws out everything but the leading order, error^16 suppression sounds pretty good...
February 5, 2025 at 11:47 PM
Curious how did you get the initial depth as 4 specifically? guessing here that a minimum of 3 time steps arise from pairwise gates between 3 pairs of qubits, and an extra gate somewhere?
Will check out the relevant section for technical details
February 5, 2025 at 8:52 PM
I see, it's depth 1 exactly, not just depth O(1). That would be a pretty specialized code indeed.
Pieceably transversal CCZs (which are applicable to arbitrary CSS codes) are targeted, but they would need a depth of O(d).
Interesting to see how much better tailored targeted codes can do!
February 5, 2025 at 7:05 PM
quick edit in my previous comment: the adapters were designed for LDPC regime, but simplifications for higher-weight codes would only make it easier to teleport info. But this is all side-tracking from the main story, for which I'll check out your paper.
February 5, 2025 at 6:53 PM
ah so the motivation is towards code construction tailored towards these gates rather than a generic gate scheme. Pretty neat! One can still hook these codes up to arbitrary LDPC codes using our adapters (arxiv.org/abs/2410.03628) for using these more generically in other codes.
February 5, 2025 at 6:47 PM
Congrats on these results on a very interesting problem -- Looking forward to reading this work! Are the check weights bounded during the CCZ circuit? (If not by constants, then what is the extent to which they increase?)
February 5, 2025 at 3:56 PM
Congrats! Curious, how did you verify the quantum computer's output is correct? (due to inability to reproduce this classically in feasible time)
December 10, 2024 at 10:38 PM
ahhh it's LDPC specific. thanks for clarifying!
November 24, 2024 at 6:39 PM
thanks! ok i see why good soundness isn't contained in the good confinement condition (as small syndromes can be caused by large errors).
Reg the other way around (good confinement ⊆ good soundness), it's also somehow implicit that small errors trigger a small syndrome?
my current guess it's the same inequality (f(|σ(e)|) ≥ |e|_red) , but enforced on a smaller set of errors to get a weaker condition.
November 24, 2024 at 6:34 PM
my current guess it's the same inequality (f(|σ(e)|) ≥ |e|_red) , but enforced on a smaller set of errors to get a weaker condition.
November 24, 2024 at 4:19 PM