Christopher K. Long
@christopher-k-long.bsky.social
4th year PhD Student at the University of Cambridge focusing on Quantum Computing
(he/him)
Google Scholar: https://scholar.google.com/citations?user=GRSIcsEAAAAJ
GitHub: https://github.com/Christopher-K-Long
ORCiD: https://orcid.org/0009-0001-3230-942X
(he/him)
Google Scholar: https://scholar.google.com/citations?user=GRSIcsEAAAAJ
GitHub: https://github.com/Christopher-K-Long
ORCiD: https://orcid.org/0009-0001-3230-942X
Wish I could have gone, looking forward to #QuiDiQua4!
November 11, 2025 at 7:15 AM
Wish I could have gone, looking forward to #QuiDiQua4!
Thank you for sharing this! Please give us an update of you hear back from Springer Nature.
November 7, 2025 at 6:08 AM
Thank you for sharing this! Please give us an update of you hear back from Springer Nature.
At a glance this looks like it considers higher orders than Fermi's Golden rule so should give a better estimate. I hadn't thought about phonon spin coupling—which seems important in your use case. Phonon spin coupling could also be studied with Fermi's Golden rule. But higher orders are better.
November 3, 2025 at 7:31 PM
At a glance this looks like it considers higher orders than Fermi's Golden rule so should give a better estimate. I hadn't thought about phonon spin coupling—which seems important in your use case. Phonon spin coupling could also be studied with Fermi's Golden rule. But higher orders are better.
I think being hit by a meteroid might be harder to error correct than by a few cosmic rays...
November 3, 2025 at 7:22 PM
I think being hit by a meteroid might be harder to error correct than by a few cosmic rays...
Let me know if this helps :)
October 30, 2025 at 7:02 AM
Let me know if this helps :)
Note due to approximations the rule breaks down for large t. Differentiating this at t=0 will give the initial rate, R, where the approximations are most valid. The if amplitude damping noise is modeled as 1-e^{-t/T1} then differentiating at zero we can fit for T1 and we find T1=1/R.
October 30, 2025 at 7:02 AM
Note due to approximations the rule breaks down for large t. Differentiating this at t=0 will give the initial rate, R, where the approximations are most valid. The if amplitude damping noise is modeled as 1-e^{-t/T1} then differentiating at zero we can fit for T1 and we find T1=1/R.
I don't know anything about diradical molecules, but hopeful the following is helpful:
In the stack I retain the sinc terms. You can either approx these as delta function first or just integrate the probability over the emission frequency. This will give total probability of emission after a time t.
In the stack I retain the sinc terms. You can either approx these as delta function first or just integrate the probability over the emission frequency. This will give total probability of emission after a time t.
October 30, 2025 at 7:02 AM
I don't know anything about diradical molecules, but hopeful the following is helpful:
In the stack I retain the sinc terms. You can either approx these as delta function first or just integrate the probability over the emission frequency. This will give total probability of emission after a time t.
In the stack I retain the sinc terms. You can either approx these as delta function first or just integrate the probability over the emission frequency. This will give total probability of emission after a time t.
It looks like Bluesky doesn't like transparent images. Here is take two:
October 28, 2025 at 5:58 PM
It looks like Bluesky doesn't like transparent images. Here is take two:
"A good description of the phase estimation algorithm can be found in Mosca's Ph.D. thesis"—of which I found a copy here:
www.karlin.mff.cuni.cz/~holub/soubo...
(4/4)
www.karlin.mff.cuni.cz/~holub/soubo...
(4/4)
www.karlin.mff.cuni.cz
October 28, 2025 at 5:53 PM
"A good description of the phase estimation algorithm can be found in Mosca's Ph.D. thesis"—of which I found a copy here:
www.karlin.mff.cuni.cz/~holub/soubo...
(4/4)
www.karlin.mff.cuni.cz/~holub/soubo...
(4/4)
Cleve, Ekert, Macchiavello and Mosca (doi.org/10.1098/rspa...) "integrated several of the techniques of Shor and Kitaev"—section 5 and figure 6 present the algorithm as we know it today.
(3/4)
(3/4)
Quantum algorithms revisited | Proceedings of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences
Quantum computers use the quantum interference of different computational paths to
enhance correct outcomes and suppress erroneous outcomes of computations. A common
pattern underpinning quantum algor...
doi.org
October 28, 2025 at 5:53 PM
Cleve, Ekert, Macchiavello and Mosca (doi.org/10.1098/rspa...) "integrated several of the techniques of Shor and Kitaev"—section 5 and figure 6 present the algorithm as we know it today.
(3/4)
(3/4)
A quick check in Nielsen and Chuang (Chapter 5, History and further reading, page 246 in my copy):
Kitaev introduced the phase estimation with a single output bit (arxiv.org/abs/quant-ph...).
(2/4)
Kitaev introduced the phase estimation with a single output bit (arxiv.org/abs/quant-ph...).
(2/4)
Quantum measurements and the Abelian Stabilizer Problem
We present a polynomial quantum algorithm for the Abelian stabilizer problem which includes both factoring and the discrete logarithm. Thus we extend famous Shor's results. Our method is based on a procedure for measuring an eigenvalue of a unitary operator. Another application of this procedure is a polynomial quantum Fourier transform algorithm for an arbitrary finite Abelian group. The paper also contains a rather detailed introduction to the theory of quantum computation.
arxiv.org
October 28, 2025 at 5:53 PM
A quick check in Nielsen and Chuang (Chapter 5, History and further reading, page 246 in my copy):
Kitaev introduced the phase estimation with a single output bit (arxiv.org/abs/quant-ph...).
(2/4)
Kitaev introduced the phase estimation with a single output bit (arxiv.org/abs/quant-ph...).
(2/4)
I meant the one with the QFT (diagram from Wikipedia below). I've always heard it called Kitaev's QPEA. In the thread is some history—it looks like many worked on it. The algorithm is HSP with the hiding function given by the sequence of controlled unitaries, and the period being the phase.
(1/4)
(1/4)
October 28, 2025 at 5:53 PM
I meant the one with the QFT (diagram from Wikipedia below). I've always heard it called Kitaev's QPEA. In the thread is some history—it looks like many worked on it. The algorithm is HSP with the hiding function given by the sequence of controlled unitaries, and the period being the phase.
(1/4)
(1/4)
I think seeing the relation between Kitaev's phase estimation algorithm and the hidden subgroup problem algorithm is useful. That said it is definitely good that students know it isn't the only or optimal way to do it.
October 28, 2025 at 7:11 AM
I think seeing the relation between Kitaev's phase estimation algorithm and the hidden subgroup problem algorithm is useful. That said it is definitely good that students know it isn't the only or optimal way to do it.
For T1 you can use Fermi's Golden rule. Here is a post I made a few years ago for absorbing a photon:
physics.stackexchange.com/a/649933/305...
Keep the emission term instead. Also you will probably need more than minimal couping to the EM field to get the spin flip on emission.
physics.stackexchange.com/a/649933/305...
Keep the emission term instead. Also you will probably need more than minimal couping to the EM field to get the spin flip on emission.
What happens to an electron if given quantized energy to jump to a full orbital?
Let's consider the element neon. Its ground-state electron configuration is: $1s^2 2s^2 2p^6$.
What would happen if enough energy was given for one electron in the $1s$ orbital to jump to the $2s$
physics.stackexchange.com
October 25, 2025 at 10:38 AM
For T1 you can use Fermi's Golden rule. Here is a post I made a few years ago for absorbing a photon:
physics.stackexchange.com/a/649933/305...
Keep the emission term instead. Also you will probably need more than minimal couping to the EM field to get the spin flip on emission.
physics.stackexchange.com/a/649933/305...
Keep the emission term instead. Also you will probably need more than minimal couping to the EM field to get the spin flip on emission.
PySTE now has pre-built wheels for Python 3.14!
October 19, 2025 at 10:54 PM
PySTE now has pre-built wheels for Python 3.14!
That makes sense. I would be interested in the slides afterwards is Alex is happy to share them.
October 16, 2025 at 2:33 PM
That makes sense. I would be interested in the slides afterwards is Alex is happy to share them.
Do you know if the talk will be recorded? Unfortunately, I am teaching at this time.
October 16, 2025 at 1:17 PM
Do you know if the talk will be recorded? Unfortunately, I am teaching at this time.
I guess it's time I release a 3.14 pre-built version of PySTE:
pypi.org/project/py-s...
pypi.org/project/py-s...
py-ste
A Python package for evolving unitaries and states under the Schrödinger equation using first-order Suzuki-Trotter and computing switching functions.
pypi.org
October 16, 2025 at 12:33 PM
I guess it's time I release a 3.14 pre-built version of PySTE:
pypi.org/project/py-s...
pypi.org/project/py-s...
Just created a starter package to find cool ML for quantum people here. Please help me find others and self-nominate! (i am new since yesterday, if this is supposed to be differently handled, let me know, thx hah)
go.bsky.app/357wFNf
go.bsky.app/357wFNf
October 12, 2025 at 8:07 AM
Just created a Quantum Computing Starter Pack. Please reach out if I missed to add you.
go.bsky.app/KBgRwmZ
go.bsky.app/KBgRwmZ
October 12, 2025 at 8:07 AM
go.bsky.app/75SvR2M - Who am I missing?
~got bored this afternoon, do forgive me. But on a serious note would love to know who I haven't discovered on here yet (or mistakenly omitted due to the sheer amount of people)
~got bored this afternoon, do forgive me. But on a serious note would love to know who I haven't discovered on here yet (or mistakenly omitted due to the sheer amount of people)
October 12, 2025 at 8:07 AM
Our starter pack of quantum PhD students is now full! (Unfortunately Bluesky caps it at 150.) We're happy to report that we have rescued at least 36 souls from X who joined Bluesky via our starter pack!
go.bsky.app/AUTn1di
go.bsky.app/AUTn1di
Quantum PhD students
Join the conversation
go.bsky.app
October 12, 2025 at 8:07 AM