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Dulwich Quantum Computing
@dulwichquantum.bsky.social
2.3K followers 1.2K following 1.6K posts
Parody quantum computing startup from South London dulwichquantum.github.io
Parody quantum computing startup from South London dulwichquantum.github.io
![Definition 2.1 (Felinity of a quantum state). For a n-qubit state ρ, the felinity of ρ, F n(ρ) ∈ [0, 1] is defined as...](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:tepknacn7qtpcddry35b3g2x/bafkreiewfupqfpxk46afnjvsxlwvhnsx7ng6tmnxs7bonkpwn362aqa5oq)
![This is indeed a surprising result, provided that every piece can be confidently verified by a third party and that all assumptions can be further justified. Since this work appears to make more assumptions than prior work, that somewhat weakens the baseline.
Below, I list all 11 places in the paper that contain “assume” or related forms:
Assumes non-local connectivity.
Here, we assume a 1 ms stabilizer measurement cycle.
We assume that each surgery gadget is implemented in (\tau_s \approx 2d/3) code cycles, where (d) denotes the distance of the processor code.
We assume that each layer of surgery takes (\tau_{\mathrm{cult.s}} = 2d_s/3) code cycles, which often minimizes the total logical error rate.
In the above, we assumed that for each (C_i), the involved (m_i) qubits are read from memory at the beginning and written back to memory at the end.
For the balanced architecture, we assume that (2q_a < k_p), so that the processor can store the (2q_a) qubits needed for unary iteration while still leaving enough space to apply the word operators.
For the ECC-256 algorithm, based on compilations in [116--120], we assume the following split in the Toffoli count among controlled adders, adders, and lookups:
40% for 256-bit adders,
50% for 256-bit controlled adders,
10% for lookups with 16 address bits and word size 256.
In addition, we assume the existence of logical gadgets capable of measuring many logically disjoint PPMs on high-rate codes in parallel.
For (P < 600) ((P \geq 600)), we assume processor encoding rates of (r = 20\%) ((r = 30\%)), based on upcoming work [125].
We assume that these codes have the same rate as the processor, except when (P < 100), where we assume a lower encoding rate of 4% to allow transversal coupling of smaller block sizes (e.g., the bb18 code).
To account for larger codes and more complex PPMs, we consider (\gamma = 1\text{--}3) and plot results for (\gamma = 2…](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:tepknacn7qtpcddry35b3g2x/bafkreicc23udfvkovxqtgls47l7au3v3il3a2k4cfc75orxh6fdpn24px4)
![Many of the potential applications of Hamiltonian simulation are not algorithms themselves, but
rather, the idea that having a better understanding of certain physical or chemical systems would likely
lead to new scientific and technological breakthroughs. Some of these are well worked out ideas (for
example, nitrogen fixation [RWS+17]), but many of them are very tenuous, which unfortunately does
not stop popular science news, and technology-enthusiasts who have decided to make a career talking
a lot about quantum computing without really understanding it, from treating such applications as
being just around the corner. You will find headlines and ted talks claiming quantum computers can
solve every futuristic-sounding problem, including fixing climate change [mtl], curing cancer [Kak24],
and finding the secret to immortality [Gre20]. I mean, science could solve any of these (but could it?),
and faster Hamiltonian simulation would mean we can do better science, so. . . The reality is, there
probably will be many applications to being able to simulate physical systems, but we do not yet know
what they will be. We will not discuss applications of Hamiltonian simulation in this course, but it
is important to understand that there is a lot of hype around quantum computing, some of which is
justified, and some of which is not.](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:tepknacn7qtpcddry35b3g2x/bafkreibcs6y26budwxemzcdm4sxf4ltootd5f76rwvr4efnbebvrc2nm3a)
![[mtl] Too many to list. 2](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:tepknacn7qtpcddry35b3g2x/bafkreiaph4etvskbsokocvaatfdbnslz77vyl5tlvlkj6yav62hg7lzbwi)
