Jeongrak Son
@perp-waterfall.bsky.social
Last week I defended my thesis "Quantum Qomrades: Catalysts in Resource Theories and Memories in Dynamic Programming". This journey was possible thanks to all my human comrades, especially my amazing adviser @nellynghy.bsky.social !
September 9, 2025 at 6:55 AM
Last week I defended my thesis "Quantum Qomrades: Catalysts in Resource Theories and Memories in Dynamic Programming". This journey was possible thanks to all my human comrades, especially my amazing adviser @nellynghy.bsky.social !
Reposted by Jeongrak Son
Our tutorial "A friendly guide to exorcising Maxwell's demon" (journals.aps.org/prxquantum/p...) is out!
The big question after the tutorial is whether I’m finally done drawing demons?
The big question after the tutorial is whether I’m finally done drawing demons?
August 11, 2025 at 4:29 PM
Our tutorial "A friendly guide to exorcising Maxwell's demon" (journals.aps.org/prxquantum/p...) is out!
The big question after the tutorial is whether I’m finally done drawing demons?
The big question after the tutorial is whether I’m finally done drawing demons?
This is actually the first no-go result for robust catalysis (i.e. catalytic transformations that are catalytic even with small state preparation noise) outside completely resource non-generating operations. Next step: robust catalysis in LOCC or stabiliser operations?🥴🥴
We learnt that thermal operations strike a really sweet spot between encompassing non-Markovian effects in the form of robust catalysis, therefore favouring it over subsets of the theory. At the same, any other superset of the theory would require a non-equilibrium environment!
July 23, 2025 at 7:55 AM
This is actually the first no-go result for robust catalysis (i.e. catalytic transformations that are catalytic even with small state preparation noise) outside completely resource non-generating operations. Next step: robust catalysis in LOCC or stabiliser operations?🥴🥴
Reposted by Jeongrak Son
A fun project with Seok Hyung, Jeongrak ( @perp-waterfall.bsky.social ), @nellynghy.bsky.social , and Paul Boes. We dusted off some old notes because there seemed to be renewed interest in what differentiates thermal operations from Gibbs-preserving maps.
arxiv.org/abs/2507.16637
arxiv.org/abs/2507.16637
July 23, 2025 at 7:27 AM
A fun project with Seok Hyung, Jeongrak ( @perp-waterfall.bsky.social ), @nellynghy.bsky.social , and Paul Boes. We dusted off some old notes because there seemed to be renewed interest in what differentiates thermal operations from Gibbs-preserving maps.
arxiv.org/abs/2507.16637
arxiv.org/abs/2507.16637
Reposted by Jeongrak Son
Years down the road, Jeongrak and I were trying to figure out whether robust catalytic advantage exists for thermal operations. We then realized that the conceptual key was hidden in those early, unannounced results by our friends all along!
arxiv.org/abs/2412.06900
arxiv.org/abs/2412.06900
Robust Catalysis and Resource Broadcasting: The Possible and the Impossible
In resource theories, catalysis refers to the possibility of enabling otherwise inaccessible quantum state transitions by providing the agent with an auxiliary system, under the condition that this au...
arxiv.org
July 23, 2025 at 3:07 AM
Years down the road, Jeongrak and I were trying to figure out whether robust catalytic advantage exists for thermal operations. We then realized that the conceptual key was hidden in those early, unannounced results by our friends all along!
arxiv.org/abs/2412.06900
arxiv.org/abs/2412.06900
Reposted by Jeongrak Son
Whether or not you're a fan of thermal operations, there's something fundamentally special about them: by pinning down what it means to equilibrate, thermal operations uniquely emerge! With this, we also uncover nice hierarchy of unital channels, in contrast with the classical Birkhoff theorem.
July 23, 2025 at 3:07 AM
Whether or not you're a fan of thermal operations, there's something fundamentally special about them: by pinning down what it means to equilibrate, thermal operations uniquely emerge! With this, we also uncover nice hierarchy of unital channels, in contrast with the classical Birkhoff theorem.
Reposted by Jeongrak Son
Grover's algorithm is reinterpreted as a product formula approximation of imaginary-time evolution in a new paper.
@marekgluza.mathstodon.xyz.ap.brid.gy
@perp-waterfall.bsky.social
@nellynghy.bsky.social
@qzoeholmes.bsky.social
arxiv.org/abs/2507.15065
@marekgluza.mathstodon.xyz.ap.brid.gy
@perp-waterfall.bsky.social
@nellynghy.bsky.social
@qzoeholmes.bsky.social
arxiv.org/abs/2507.15065
Grover's algorithm is an approximation of imaginary-time evolution
We reveal the power of Grover's algorithm from thermodynamic and geometric perspectives by showing that it is a product formula approximation of imaginary-time evolution (ITE), a Riemannian gradient f...
arxiv.org
July 22, 2025 at 1:51 PM
Grover's algorithm is reinterpreted as a product formula approximation of imaginary-time evolution in a new paper.
@marekgluza.mathstodon.xyz.ap.brid.gy
@perp-waterfall.bsky.social
@nellynghy.bsky.social
@qzoeholmes.bsky.social
arxiv.org/abs/2507.15065
@marekgluza.mathstodon.xyz.ap.brid.gy
@perp-waterfall.bsky.social
@nellynghy.bsky.social
@qzoeholmes.bsky.social
arxiv.org/abs/2507.15065
Reposted by Jeongrak Son
Finally, we show that quantum signal processing can be used to implement imaginary time evolution for unstructured search without post selection.
And this enables us to design a new `fixed-point' quantum search algorithm
i.e., a Grover type algorithm that never overshoots the solution
And this enables us to design a new `fixed-point' quantum search algorithm
i.e., a Grover type algorithm that never overshoots the solution
July 22, 2025 at 12:25 PM
Finally, we show that quantum signal processing can be used to implement imaginary time evolution for unstructured search without post selection.
And this enables us to design a new `fixed-point' quantum search algorithm
i.e., a Grover type algorithm that never overshoots the solution
And this enables us to design a new `fixed-point' quantum search algorithm
i.e., a Grover type algorithm that never overshoots the solution
Reposted by Jeongrak Son
Here's a new perspective on why Grover’s algorithm algorithm works:
Unstructured search can be written as ground state problem.
Then Grover's is just a product formula approximation of imaginary-time evolution
or, equivalently, a Riemannian gradient flow on SU(d)
to find this ground state.
Unstructured search can be written as ground state problem.
Then Grover's is just a product formula approximation of imaginary-time evolution
or, equivalently, a Riemannian gradient flow on SU(d)
to find this ground state.
July 22, 2025 at 12:25 PM
Here's a new perspective on why Grover’s algorithm algorithm works:
Unstructured search can be written as ground state problem.
Then Grover's is just a product formula approximation of imaginary-time evolution
or, equivalently, a Riemannian gradient flow on SU(d)
to find this ground state.
Unstructured search can be written as ground state problem.
Then Grover's is just a product formula approximation of imaginary-time evolution
or, equivalently, a Riemannian gradient flow on SU(d)
to find this ground state.
Reposted by Jeongrak Son
Check out this arXiv paper if you're interested!
arxiv.org/abs/2507.15065
arxiv.org/abs/2507.15065
Grover's algorithm is an approximation of imaginary-time evolution
We reveal the power of Grover's algorithm from thermodynamic and geometric perspectives by showing that it is a product formula approximation of imaginary-time evolution (ITE), a Riemannian gradient f...
arxiv.org
July 22, 2025 at 7:54 AM
Check out this arXiv paper if you're interested!
arxiv.org/abs/2507.15065
arxiv.org/abs/2507.15065
Reposted by Jeongrak Son
Our Grover preprint just popped up! (with Yudai Suzuki, @qzoeholmes.bsky.social, @marekgluza.mathstodon.xyz.ap.brid.gy, @nellynghy.bsky.social, @perp-waterfall.bsky.social)
Turns out… Grover's algorithm is secretly moonlighting as a first-order approximation to the imaginary time evolution!
Turns out… Grover's algorithm is secretly moonlighting as a first-order approximation to the imaginary time evolution!
July 22, 2025 at 7:50 AM
Our Grover preprint just popped up! (with Yudai Suzuki, @qzoeholmes.bsky.social, @marekgluza.mathstodon.xyz.ap.brid.gy, @nellynghy.bsky.social, @perp-waterfall.bsky.social)
Turns out… Grover's algorithm is secretly moonlighting as a first-order approximation to the imaginary time evolution!
Turns out… Grover's algorithm is secretly moonlighting as a first-order approximation to the imaginary time evolution!
Our paper (w/ Marek, @ryujitakagi.bsky.social, @nellynghy.bsky.social ) on Quantum Dynamic Programming has recently been published in PRL: journals.aps.org/prl/abstract...
Xin Yi from CQT wrote a great highlight article for this paper: www.cqt.sg/highlight/20...
Xin Yi from CQT wrote a great highlight article for this paper: www.cqt.sg/highlight/20...
Quantum Dynamic Programming
We introduce a quantum extension of dynamic programming, a fundamental computational method that efficiently solves recursive problems using memory. Our innovation lies in showing how to coherently ge...
journals.aps.org
May 21, 2025 at 8:54 AM
Our paper (w/ Marek, @ryujitakagi.bsky.social, @nellynghy.bsky.social ) on Quantum Dynamic Programming has recently been published in PRL: journals.aps.org/prl/abstract...
Xin Yi from CQT wrote a great highlight article for this paper: www.cqt.sg/highlight/20...
Xin Yi from CQT wrote a great highlight article for this paper: www.cqt.sg/highlight/20...
Thm.2 is derived from Eq. (16), which I am particularly fond of. This equation shows that any linear combination of a Hermitian matrix and the identity can be applied to a quantum state exactly and deterministically (given one can synthesise the exponential of a commutator).
April 4, 2025 at 9:25 AM
Thm.2 is derived from Eq. (16), which I am particularly fond of. This equation shows that any linear combination of a Hermitian matrix and the identity can be applied to a quantum state exactly and deterministically (given one can synthesise the exponential of a commutator).
Reposted by Jeongrak Son
Today we posted a paper showing how a double-bracket quantum algorithm can implement quantum signal processing (DB-QSP), i.e., apply polynomial functions of operators to states.
Crucially our approach doesn't need any post-selection - but this comes at the expense of increased circuit depths.
Crucially our approach doesn't need any post-selection - but this comes at the expense of increased circuit depths.
April 3, 2025 at 5:16 PM
Today we posted a paper showing how a double-bracket quantum algorithm can implement quantum signal processing (DB-QSP), i.e., apply polynomial functions of operators to states.
Crucially our approach doesn't need any post-selection - but this comes at the expense of increased circuit depths.
Crucially our approach doesn't need any post-selection - but this comes at the expense of increased circuit depths.
Reposted by Jeongrak Son
A new paper introduces Double-Bracket QSP (DB-QSP), a novel quantum signal processing approach that eliminates the need for auxiliary qubits and post-selection by using approximate unitary synthesis.
arxiv.org/abs/2504.01077
arxiv.org/abs/2504.01077
Double-bracket algorithm for quantum signal processing without post-selection
Quantum signal processing (QSP), a framework for implementing matrix-valued polynomials, is a fundamental primitive in various quantum algorithms. Despite its versatility, a potentially underappreciat...
arxiv.org
April 3, 2025 at 11:51 AM
A new paper introduces Double-Bracket QSP (DB-QSP), a novel quantum signal processing approach that eliminates the need for auxiliary qubits and post-selection by using approximate unitary synthesis.
arxiv.org/abs/2504.01077
arxiv.org/abs/2504.01077
Reposted by Jeongrak Son
Nelly Ng "Robust Catalysis and Resource Broadcasting: The Possible and the Impossible" #QuantumResources2025
I asked if there might be implications for Deutschian closed timelike curves. When I asked my question, I wasn't so serious, but thinking more afterwards, I think there is more to explore
I asked if there might be implications for Deutschian closed timelike curves. When I asked my question, I wasn't so serious, but thinking more afterwards, I think there is more to explore
March 18, 2025 at 12:14 AM
Nelly Ng "Robust Catalysis and Resource Broadcasting: The Possible and the Impossible" #QuantumResources2025
I asked if there might be implications for Deutschian closed timelike curves. When I asked my question, I wasn't so serious, but thinking more afterwards, I think there is more to explore
I asked if there might be implications for Deutschian closed timelike curves. When I asked my question, I wasn't so serious, but thinking more afterwards, I think there is more to explore
Another paper of the week! scirate.com/arxiv/2412.0...
In resource theories, catalysis provides many amazing advantages. However, it turns out that whenever there is system preparation error, most of them stop being catalytic.
Fret not! We introduced a new class that is robust under such errors.
In resource theories, catalysis provides many amazing advantages. However, it turns out that whenever there is system preparation error, most of them stop being catalytic.
Fret not! We introduced a new class that is robust under such errors.
December 11, 2024 at 8:10 AM
Another paper of the week! scirate.com/arxiv/2412.0...
In resource theories, catalysis provides many amazing advantages. However, it turns out that whenever there is system preparation error, most of them stop being catalytic.
Fret not! We introduced a new class that is robust under such errors.
In resource theories, catalysis provides many amazing advantages. However, it turns out that whenever there is system preparation error, most of them stop being catalytic.
Fret not! We introduced a new class that is robust under such errors.
Reposted by Jeongrak Son
Nature cools things easily but getting a quantum computer to do it is hard!
Give us an approx ground state, we present an algorithm that approximates imaginary time evolution to:
- Cool that state by an amount proportional to its energy fluctuations
- Increase its fidelity with the ground state
Give us an approx ground state, we present an algorithm that approximates imaginary time evolution to:
- Cool that state by an amount proportional to its energy fluctuations
- Increase its fidelity with the ground state
December 9, 2024 at 12:56 PM
Nature cools things easily but getting a quantum computer to do it is hard!
Give us an approx ground state, we present an algorithm that approximates imaginary time evolution to:
- Cool that state by an amount proportional to its energy fluctuations
- Increase its fidelity with the ground state
Give us an approx ground state, we present an algorithm that approximates imaginary time evolution to:
- Cool that state by an amount proportional to its energy fluctuations
- Increase its fidelity with the ground state
New preprint on arXiv!
scirate.com/arxiv/2412.0...
Quantum imaginary-time evolution (QITE) is amazing, but its compilation is not straightforward. We found an iterative way of doing this, using the equivalence of QITE and double-bracket flows.
scirate.com/arxiv/2412.0...
Quantum imaginary-time evolution (QITE) is amazing, but its compilation is not straightforward. We found an iterative way of doing this, using the equivalence of QITE and double-bracket flows.
Double-bracket quantum algorithms for quantum imaginary-time evolution
Efficiently preparing approximate ground-states of large, strongly correlated systems on quantum hardware is challenging and yet nature is innately adept at this. This has motivated the study of therm...
scirate.com
December 9, 2024 at 9:21 AM
New preprint on arXiv!
scirate.com/arxiv/2412.0...
Quantum imaginary-time evolution (QITE) is amazing, but its compilation is not straightforward. We found an iterative way of doing this, using the equivalence of QITE and double-bracket flows.
scirate.com/arxiv/2412.0...
Quantum imaginary-time evolution (QITE) is amazing, but its compilation is not straightforward. We found an iterative way of doing this, using the equivalence of QITE and double-bracket flows.
Reposted by Jeongrak Son
Double-bracket quantum algorithms for quantum imaginary-time evolution
https://arxiv.org/pdf/2412.04554
Marek Gluza, Jeongrak Son, Bi Hong Tiang, Yudai Suzuki, Zoë Holmes, Nelly H. Y. Ng
https://arxiv.org/pdf/2412.04554
Marek Gluza, Jeongrak Son, Bi Hong Tiang, Yudai Suzuki, Zoë Holmes, Nelly H. Y. Ng
https://arxiv.org/abs/2412.04554
arXiv abstract link
arxiv.org
December 9, 2024 at 3:03 AM
Double-bracket quantum algorithms for quantum imaginary-time evolution
https://arxiv.org/pdf/2412.04554
Marek Gluza, Jeongrak Son, Bi Hong Tiang, Yudai Suzuki, Zoë Holmes, Nelly H. Y. Ng
https://arxiv.org/pdf/2412.04554
Marek Gluza, Jeongrak Son, Bi Hong Tiang, Yudai Suzuki, Zoë Holmes, Nelly H. Y. Ng