Daniel Malz

Theoretical physicist, interested in quantum optics, quantum information, and quantum technologies. Assistant Professor at the University of Copenhagen

[Physical Review X @PhysRevX]

To investigate #quantum many-body problems, scientists compared quantum and classical dynamics using random permutation circuits and random unitary circuits, showing that both systems have similar behaviors.

Read the paper: https://t.co/hS7udYnk5v

[Daniel Malz @danielmalz]

@PhysRevX One motivation to consider random permutation circuits is that they are a microscopic model for generic classical reversible dynamics. In this mathematically precise setting, we can have a close look at similarities and differences of quantum and classical information spreading

[Lorenzo Pacchiardi @LPacchiardi]

[🌎English version]
📢 Introducing 🌐https://t.co/8ZmWc1zlhq, a website for finding a job in Italian universities and research institutes.

1/n

[Daniel Malz @danielmalz]

@QuElmanS Thanks and very good question! We have not considered that in this work, but I wouldn't be surprised if you could use the map between isoTNS and circuits to construct nice examples of projected ensembles

[Daniel Malz @danielmalz]

📢 new preprint: Computational complexity of isometric tensor network states
https://t.co/7lOkQjhth2

IsoTNS are versatile variational states, but how easy is it to compute their properties?

We relate this to widely studied complexity transitions in quantum dynamics

🧵 1/5

[Daniel Malz @danielmalz]

For more percolation, 2D state to 1+1D dynamics mappings, and nice tensor pictures, head to our preprint at https://t.co/7lOkQjhth2.

I've had a great time putting this together with Rahul Trivedi! 🙌

🧵 5/5

[Daniel Malz @danielmalz]

What about sampling from the whole state?

Sampling maps to monitored quantum circuit dynamics, which is known to undergo measurement-induced phase transitions to easy phases.

We can construct a family of states interpolating from a provably hard to an easy phase

🧵 4/5

[Sabine Hossenfelder @skdh]

I've been working on a video about net zero -- what is it, how will we get there, how far are we along the way, etc. Just finished recording. Research has been extremely depressing.

In an nutshell, every serious source (incl the IPCC) agrees that there's no way we'll reach net zero without substantial and fast investment into extensive carbon removal. We're talking about an increase by at least a factor 100 (!) by 2050. Yet this carbon removal doesn't even exist in plans. That's right, even if you add up all the plans that have been put forward -- which I'd say are a pie in the sky already -- it wouldn't work.

The cherry on the rotten tart of net zero are environmental groups (infamously, Greenpeace) who are opposed to carbon capture and storage (CCS) at fossil fuel plants, and since most people can't tell the difference between CCS and carbon removal, it's getting in the way of net zero. Like with nuclear power, it's increasingly the so-called "environmentalists" who are in the way of protecting the environment.

I'm not a fan of offshore drilling either, but complaining about CCS is broken logic.

I'll have more details about this in the upcoming video (will be out in in a few weeks) but the more I think about it, the more I feel like the origin of this problem is presumably well-meaning activists (let's not name names) whose we-can-do-it attitude has made people think reaching net zero is much easier than it really is.

These are all difficult topics with many nuances, but if I was in charge of running the world I'd quit. Sorry, I meant to say if I was in charge of running the world, my course of action would be:

(a) Nuclear power everywhere it's geographically safe enough. I know that no one really likes nuclear power, but it's the least bad option to decarbonize energy intensive industry quickly.
(b) Bio energy with carbon capture and storage everywhere there's large amounts of quickly re-growing biomass available, it would make sense for rich countries to finance such facilities elsewhere
(c) Expand and modernize the electric grid asap because without that nothing else will work -- according to a recent IEA report there's 3000 GW (!) of renewable energy power plants waiting to be hooked up onto electric grids that can't cope
(d) electric vehicles (the world is actually doing quite well with that one, if it wasn't for point (c))
(e) synthetic fuels produced with renewable energy -- it's energetically hugely inefficient but realistically the only way to decarbonize aviation quickly, you may want to do this in regions with reliable sunshine (Australia, Africa)

The reason I didn't say anything about wind and solar is not that those are unimportant but that those are faict going fine.

My twitter feed has been greatly enriched by @EliotJacobson who is as doom as doom gets which I think is the appropriate reaction in the current situation.

[Alvaro M. Alhambra @AlhambraAlvaro]

We at the Quantum group @ift_uam_csic are offering a 2-year postdoc, to work on a wide range of topics on quantum matter and information. Come join us in sunny Madrid!

[Daniel Malz @danielmalz]

@DeptofPhysics @MeteAtature Congrats, Mete, I wish you all the best! The department will be in great hands 🙌

[Daniel Malz @danielmalz]

There are many open positions to join the vibrant Copenhagen research community, including in my group. Apply by 15th Nov!

[QMATH @QMATH_KU]

We are looking for PhD students interested in the mathematical theory of quantum mechanics and quantum computation at QMATH in Copenhagen! Applications go through the call https://t.co/4nw1kU1FLR

[Johannes Knörzer @KnorzerJohannes]

Excited to co-organise the 804th #HeraeusSeminar with Jasmin Meinecke & Matthias Zimmermann! Focus on #quantumcomputing and #quantumsimulation in the #nisq era, with a great line-up of speakers. Join us from January 14 - 18, 2024 in Bad Honnef, Germany!

[Daniel Malz @danielmalz]

it's been a really fun and exciting collaboration together with Zhi-Yuan Wei, Yorgos Styliaris and Ignacio Cirac!

[Daniel Malz @danielmalz]

📢 new preprint just out: Preparation of matrix product states with log-depth quantum circuits

We give an explicit circuit to prepare normal MPS (aka unique ground states of local gapped Hamiltonians) and prove it's asymptotically optimal

https://t.co/tIJ0xcyVgU

[Daniel Malz @danielmalz]

If you add measurement + feedback, the preparation time is exponentially reduced from log N to loglog N, and you can prepare long-range correlated (non-normal MPS) in the same depth.

[QMATH @QMATH_KU]

A tenure track position on Quantum Algorithms for Chemistry and Life Sciences at the Chemistry Department of the University of Copenhagen https://t.co/7d8L9dDjzr. Looking for colleagues to join the vibrant quantum community in Copenhagen!

[Physical Review Research @PhysRevResearch]

Efficient adiabatic preparation of tensor network states, Zhi-Yuan Wei, Daniel Malz, and J. Ignacio Cirac #Quantum #QuantumInformation https://t.co/9Q4CXlOpLF