stuff is going on!

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Floquet Dynamics of a Central Spin

In today's arXiv preprint, we report interesting results from the Floquet dynamics of a Central spin. Because of the coherent, angular-momentum recoupling like, structure of the ground state and highest excited state, it is possible to polarize the central spin by driving that resonance.

The preprint can be found here: arXiv/1712.031117

All comments are again highly welcomed and appreciated!

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Richardson-Gaudin Configuration Interaction

Our manuscript on Richardson-Gaudin Configuration Interaction (RGCI) for nuclear pairing correlations appeared today on the arXiv. In this paper, we use a variationally optimized RG (varRG) state as the starting point for a complete basis set in which a realistic, non-integrable can be diagonalized.

The varRG state already yields correlation energy errors around the 1%, and the following step improves upon that in an exponential way.

There is a tight link with ideas from Similarity Renormalization Group, as the non-integrable Hamiltonian matrix in the optimized Richardson-Gaudin basis is characterized by a strong suppression in the off-diagonal part.

The preprint can be found here: arXiv/1712.01673

All comments are highly welcomed and appreciated!

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Big Data

I took a course on Big Data at UGain to jump the big hype on machine learning. I took the exam and passed. yay!

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Variational Richardson-Gaudin

Our paper on variational Richardson-Gaudin (varRG) has been published today in Physical Review B. In this paper, we propose a Richardson-Gaudin on-shell state as a variational ansatz for a finite-size spin system with inhomogeneities. More in particular, we investigate Central Spin models, and collective pairing Hamiltonians where integrability is perturbed/broken.

This would be an intractable problem, if not for the existence of nice tractable inner products [see previous post]. Intuitively, one would expect that the variationally optimal state is adiabatically connected to the ground state of the unperturbed model. We show this is not true, and excited state manifolds are also possible!!

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Inner products for Richardson-Gaudin (RG) models (iii)

Our SciPost paper has been published today! You can read all (!) the reports in the submission section and even give comments if you wish.

The whole publishing in SciPost has been an interesting trip. We received very constructive referee reports on the paper, and I would guess that the openness of the whole format has contributed to that.

Would submit again.

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Kunst & Wetenschap

Thanks to everyone for joining me at my little lecture on Kunst & Wetenschap during at the #ugent200 happening. Patric Baele of the Academy took footage, and my slides can be found here

kunstenwetenschap.pdf

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200 years UGent party!

Next Sunday (Oct 8th), we celebrate the 200y UGent birthday party. Among so many other activities, there is an Art & Science exhibition at Campus Ledeganck, including a lecture by yours truly about the intertwining of Art & Science.

Everyone's invited!

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quantum group

I have recently joined the quantum physics group of Frank Verstraete in Ghent, investigating the tight link between the Algebraic Bethe Ansatz and Matrix Product States. You can find me now in the wonderful and thriving landscape office at S9.

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WATOC2017

I will be attending WATOC2017, probably the most comprehensive conference for theoretical chemistry, next week. I will be presenting this poster on variational geminals (based on our latest arXiv paper with Pieter.

I'm poster PO2-230 in Poster Session 2. Please come over, and say hi!

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200 years UGent - Art exhibition

Next Sunday (16th of July) the art exhibition of the UGent workers association will open at the Aula in honor of the 200th birthday of the University. A couple of my recent works will be on display. More information can be found here.

The exhibition runs until Thursday, July 20th

Here's a picture of the previous exhibition. Nice location!

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EJD-TCCM

I will give an invited lecture at the 2nd Annual Meeting and Conference of the European Joint Doctorate in Theoretical Chemistry and Computational Modelling in Leuven, next week. I will talk about the seniority scheme, and how 2 is still better than 1!

Please, come over and say hi!

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Inner products for Richardson-Gaudin (RG) models (ii)

The first report of our SciPost paper is in!

Admittedly, it feels odd to find an open review online, but that is probably due to a lack of custom/habit. tbc!

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Inner products for Richardson-Gaudin (RG) models

We developed a unifying framework in which we can easily commute between Slavnov, Izergin-Borchardt and Eigenvalue-based inner-products, all based on the nice properties of Cauchy matrices and their inverse. Moreover, we established a beautiful duality between Gaudin (Slavnov) and Eigenvalue-based matrix forms.

Pieter put the paper on the arXiv, and it will be is submitted to SciPost.

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meesterlijk

Next Friday (May 19th, 2017) marks the opening of the art exhibition

MEESTERLIJK

at the CJK in Ghent

More information in the art section

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Block Product Density Matrix Embedding Theory

We published a paper in Phys. Rev. B on a variant of Density Matrix Embedding Theory (DMET), in which we propose a block-product cluster quantum state for the (variational) optimization of finite-size spin systems. After the optimization, the evaluation of properties happens in the convential DMET style.

Test calculations are performed for a 2D Antiferromagnetic Heisenberg and Kitaev-Heisenberg systems. Results are ok, except for the spin liquid phase.

Congrats to Klaas for his first paper! :-)

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Université de Nice

Next Thu/Fri, I will be visiting the Interfaces des Mathématiques et Systèmes Complexes group of Patrick Cassam-Chenaï of the Laboratoire J.A. Dieudonné at the Université de Nice.

I will be presenting some mathematical work on Richardson-Gaudin integrability.

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publons

publon: (noun m: publons) smallest quantum of peer reviewing.

Good peer reviewing is an essential academic responsability. Unfortunately, not everyone takes it so seriously. Without taking this too far, one of the issues involved is the difficulty of claiming credit. I have been recognized twice as "Valuable Referee" by Nuclear Physics A, but that does not happen too often. So, I support the initiative by publons.com, where everyone can build a refereeing profile, without chipping in on anonymity.

You can find my profile here

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medialab @ dko

Analog Deconstruction Of Digital Design in the art section

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mid-term evaluations @ dko

Some new additions in the art section

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FWO grant!

I secured a research grant from the FWO with Patrick Bultinck from the GQCG.
The title of our proposal is

Highly accurate and universally applicable electron-pair based electronic structure method

The purpose of this research project is to bring our geminals to open shells, excited states and non-orthogonal orbitals. Exciting stuff!

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