The story behind papers

Story behind the paper. This project brought together Lex Kemper's group (including Goksu, me, and Mariano) at NC State with Nick Mayhall's group at Indiana (with Arnab), who had recently developed Pauli propagation as a classical simulation tool. We began meeting regularly in late 2025 and early 2026 to explore whether the method could be extended to compute real-time two-point correlation functions, the quantities that directly connect quantum many-body theory with experiments.

The main challenge is that the number of Pauli strings grows rapidly with time, making straightforward propagation impractical. Our approach was to combine accurate short-time Pauli propagation with a positivity-based (PSD/Prony-type) time-extension method that reconstructs the long-time signal from only a limited time window. We also used Clifford-augmented matrix product states (CAMPS) to efficiently prepare the ground states needed for the correlators. Together, these ingredients enabled us to compute the dynamical structure factor of an 8×8 Heisenberg antiferromagnet, a system well beyond the reach of conventional exact methods.

Lex led the project, while I worked primarily on the CAMPS calculations and contributed to the writing. This was also Mariano's first paper—congratulations to him!

Story behind the paper. This paper started back in August 2024, when Sabhyata and I met while attending the QSIM conference at the University of Rhode Island. She had seen my SYK paper from November 2023 and expressed interest in related problems involving random all-to-all Hamiltonians. Bharath and I initially thought that fixed-depth Cartan-inspired ideas might work for this model. Sabhyata put in a lot of work, but we eventually reached the conclusion that this route was not working well enough to form a publishable result. Around this time, Bharath started his postdoc at Virginia Tech, and I had the thought that we should instead try ADAPT-VQE methods for studying models with random couplings.

Story behind the paper. This paper grew out of the question of how quantum-information diagnostics behave in a genuinely gauge-invariant lattice gauge theory going beyond quantum spin models. Instead of looking only at entanglement, we wanted to understand the role of magic as a separate computational resource in a non-Abelian lattice gauge theory. We found a paper by Cataldi et al. where the authors used a semi-link (rishon-type) dressed-site approach. I initially tried to generalize it for arbitrary cutoff but it was a bit messy. We were afraid of getting scooped (which we evaded by a week, see https://arxiv.org/abs/2606.14842), so we decided to just focus on jmax=1/2 and tried to finish the paper. I liked the project since it was very timely and connected tensor network simulations with ideas from stabilizer theory and quantum resources, giving us a way to ask which parts of the lattice gauge theory are hard for classical or Clifford-based descriptions. We finished this paper very quickly, in about two months, since we were writing the draft and coding the SRE/EE computation simulataneously. This was also Jaber's first paper. Congratulations to him!

Story behind the paper. I started working on this project while I was at Jefferson Lab during June 2025. I started my new position at NC State in September 2025 and substantially expanded the paper to address dynamical Lie algebras (DLA), and also estimate costs with QSVT methods. Joao helped me with AVQITE simulations and we could push to 20 qubits. This project sits at the intersection of quantum simulation and relativistic fermionic QFTs. The motivation was to understand how far one can push Hamiltonian methods for field theories with an arbitrary number of flavors, rather than treating the flavor number as a small fixed parameter. The Thirring and Gross--Neveu models are useful toy models that are rich enough to contain nontrivial interaction structure, symmetries, and scaling questions.

Story behind the paper. Shinichiro, Judah, and I had been collaborating on tensor projects since Summer 2023. This paper originated when Shinichiro presented our previous paper at Yukawa Institute in Kyoto. Yuya was very interested and suggested that we can likely probe critical behaviour if we can do twisted boundary conditions in the TRG setup. Shinichiro mostly worked out the detail and this was made easy based on the code I already had from 2d and 3d O(2) models previously. I checked the calculations independently. The basic idea is that this approach is a sharper diagnostics of criticality in tensor renormalization group calculations. Instead of relying only on conventional observables, the idea is to use symmetry-twisted partition functions as a controlled probe of universal information. The twist acts like a clean way to ask which sectors of the theory survive under coarse graining and how they reorganize near a critical point. What makes the story appealing is that the method is both numerical and conceptual: it gives a practical TRG observable, but it is also tied to symmetry and universality.

Story behind the paper. I had just accepted the offer from NC State to start as Assistant Research Scholar from September 2025. Lex and Yuan added me to the Slack channel for onboarding and research discussions. In one of those old chats in the channel, I found a link to Overleaf document. I requested Yuan and Lex to join the project and suggested that due to my previous papers on using continuous variables (CV) for lattice gauge theory, I can work on the review and details of that section. In this guide, we clarify range of problems where hybrid continuous-discrete-variable quantum computing can genuinely be useful in the coming decades. The subject often has two communities speaking slightly different languages: qubits and gates on one side, qumodes, Gaussian operations, and bosonic encodings on the other. The goal of the paper is to organize the common ground and identify situations where the hybrid approach is not just elegant, but practically motivated. A useful story is that continuous variables are not merely another hardware platform; they can be a natural language for bosons, gauge links, fields, and oscillator-like degrees of freedom. This paper therefore plays the role of a map for deciding when CV resources should be part of a quantum algorithmic toolbox.

Story behind the paper. I started thinking about the analytic expression for 2d classical Ising model partition function when we turn on the magnetic field during April-May 2020. I had the tool of TRG to my disposal, where I could quickly generate the data for finite fields. I started with a hypergeometric closed form expression for Onsager's result and asked the following question -- what is the simplest extension of this result to admit magnetic field. After few trials, I could come up with a good guess which I later improved. This was worked out all before end of 2020 but I did not publish it since I thought it was useless. However, in 2025, I thought there is no harm in posting on arXiv. I tried to get this published, but no one saw value in this paper, so I have left it on arXiv. Surprisingly, some of my old friends and professors, emailed and mentioned this paper saying it was a great guess.

Story behind the paper. This paper belongs to the broader effort of using lattice methods to make gauge/gravity duality quantitative. The BMN matrix model is particularly attractive because it is a deformation of the BFSS matrix model with a rich finite-temperature structure. When I was working on my first and second paper back in 2017-2018, I was asked by Simon to accompany him to a conference at ICTS, Bangalore in India. While preparing my 30-min talk for the conference, I wrote the plan for this project. Then, I suggested this with Simon, Toby, David, and Anosh. Though, we started working, we were delayed due to various reasons. In the meantime, Denjoe's group (from Dublin Institute) and another group led by Masanori studied this model. We wrote two lattice proceedings but could only finish the paper in 2024. The numerical simulations were very complicated and due to the requirement of large N, it took sometime to interpret and understand the results. However, this project did led to another earlier published paper on bosonic BMN model.

Story behind the paper. I started as a postdoc at Perimeter Institute (PI) in Fall 2019. At Perimeter, postdoctoral researchers are usually assigned to a senior faculty member. I was assigned to Pedro Viera and Guifre Vidal expected to work on S-matrix bootstrap/matrix models and tensor network methods. In October 2019, Pedro mentioned about a very interesting gapped quantum field theory which is integrable in two extreme limits and non-integrable otherwise. He suggested that it would be really interesting to do some scattering in this model using tensor networks and interpolate between two "analytically known" limits.

Soon after this discussion, three postdocs at Perimeter -- Dominik, Stefan and I started thinking about this. I obtained some initial results and explored the parameter space but did not follow up and got busy with other projects. Soon after, world was hit by COVID and PI closed. Pedro and I often discussed that this would have been a very nice paper. After about 7-8 months, in December 2020, we saw a paper posted on arXiv doing something very similar for a different case. In this paper, the Caltech group consisting of Ash, Guifre, Junyu, and John studied scattering in spin model using MPS methods (arXiv:2012.07243). We (Pedro, Dominik, and I) at PI invited Ash (who was a postdoc at PI before moving to Caltech) to give a talk discussing this paper in February 2021. Soon, we arranged a meeting and started working on this project.

This project was pretty long but the kind of elastic/inelastic scattering that we probed in an interacting quantum field theory interpolating between two integrable limits has resulted in this paper becoming a flagship scattering computation in 1+1-dimensions for both high-energy theorists and tensor network folks. One day, hopefully, our results will be further improved by AI-based or quantum computing methods. With this paper, my Weinberg-index improved to 2.

Story behind the paper. This paper is a follow-up on our work on O(3) model using continuous variables done in Fall 2023. During that project, we realized that using the relation between O(4) and SU(2) x SU(2) we could possibly construct a CV formalism of SU(2) lattice gauge theory. We came across an old paper by Creutz and found that gauge-fixing to maximal tree gauge would provide a nice connection to our CV approach. Victor and Nora did most of the heavy-lifting and spend the most time on this paper. I was guiding them and in turn, George was guiding me.

Story behind the paper. In the summer of 2024, I was thinking of following up on my recent papers and probe a sharper way of determining how much sparse can we make SYK model and still retain holographic features. I started looking at the literature and found that there is a new notion of complexity called "Krylov complexity" that can be useful. From my initial tests, I found that it was in the same range as was shown using other methods. We were partially scooped but could finish the paper in the same month. This was my longest PRD peer-review process lasting close to one year. This was also Ranadeep's first paper. Congratulations to him!

Story behind the paper. In Fall 2023, as I was finishing the paper studying Trotter complexity and out-of-time-order correlators (OTOCs) in the SYK model on IBM hardware with Asad and Bharath, I was talking to Jack in the Jefferson Lab cafe. He had been constructing thermal states using VQE methods following a particular approach. We joined hands with Bharath and Felix to prepare thermal and TFD states for SYK model. Surprisingly, we found that the quantum community had moved away from 6-10 qubit simulations and demonstrations, so we could not get this published. This likely also marks my last paper with such small systems. Only time will tell!

Story behind the paper. I was attending a conference at INT Seattle in April 2023. Shinichiro introduced himself and we started talking about TRG. I mentioned to him that back in Fall 2020, Judah and I tried to simulate the three-dimensional SU(2) principal chiral model but did not pursue due to other engagements. We were using the triad method. Shinichiro was exploring an alternative method of anisotropic TRG (ATRG). We decided to join hands and compared both methods and obtained some nice results.

Story behind the paper. This work started when I was visiting IISER Mohali in December 2021. Abhishek and Vamika were BS-MS and PhD students working with Anosh. They expressed interest in doing some TRG related project. We thought that it might be nice to explore a spin model where we have competition between integer and half-integer vortices. This led to exploring the phase diagram of generalized XY model using TRG based method using GPU acceleration. Abhishek revived this project and therefore I asked him to be the first author going away from the alphabetical ordering that we usually follow.

Story behind the paper. I wrote this paper following on our SYK model paper before/during/after vacation in Costa Rica with my wife in April 2024. Since, I extensively used Wi-Fi at Chicago O'Hare (ORD), Norfolk Airport (ORF), and Juan Santamaría International Airport (SJO), I decided to thank them in acknowledgements. This paper computed the Clifford+T-gates we need to simulate the real-time dynamics of SYK model beyond what is possible using classical computers.

Story behind the paper. These conference proceedings were based on the talk Judah presented at Fermilab in August 2023. See the story behind -- SU(2) principal chiral model with tensor renormalization group on a cubic lattice published in June 2024.

Story behind the paper. We started this project in 2021 motivated by the question as to what happens to the thermal phase structure for this four supercharge SYM theory compared to the maximally supersymmetric (sixteen) case we studied back in 2017. This is an important question (at least to us) since this might lead to really understanding the question -- what determines the holographic aspects of SYM theories. We found a phase transition, however, it was very different than maximally supersymmetric case. There was no geometry-based transition at strong couplings. Navdeep did bulk of the simulations guided at times by me.

Story behind the paper. The work on this paper started when Bharath and Asad were attending the summer bootcamp at Jefferson Lab in June 2023. They were playing around with running simulations on IBM hardware. I had no interest and wanted for formulate a nice problem where I can learn hardware experiments and error mitigation. In August 2023, when attending the Lattice conference at Fermilab, I realized that SYK model has not been studied on IBM quantum computers and since it is a very interesting model, we could obtain some nice results. Asad was familiar with OTOC computations using randomized protocols developed by other groups. I worked out the gate costs and started writing the paper while Bharath and Asad ran the hardware experiments and taught me how to run one! We did state-of-the-art error mitigation and obtained excellent results.

Story behind the paper. While being stuck on the project below (https://arxiv.org/abs/2308.06946) and finding no help around, I decided to write to George in February 2023. He had worked on CV approach to scalar field theories etc. in the past and I hoped he could help me so that we could finish this paper. George replied and suggested that we join hands. His student, Shane, a fantastic graduate student and I started working and made good progress during the summer of 2023. We could write it up in Fall 2023. This paper was the first woek where the CV approach was used to study a spin model with continuous global symmetry. This paper also led to our next paper on using CV approach for SU(2) gauge theory in 1+1 and 2+1-dimensions.

Story behind the paper. When I started my second postdoc at Jefferson Lab in Fall 2022, I was chatting with Kostas Orginos about non-linear sigma model in 1+1-dimensions. He mentioned that while the kinetic term could easily be written in terms of oscillators, the interaction term was more complicated. In October/November, I could work out the details using Schwinger boson construction. However, I was stuck and could not proceed due to various reasons! However, this roadblock led to my collaboration with George where we figured out some of this stuff. In order to keep this idea, I decided to write a conference proceedings based on the talk I presented at Lattice conference at Fermilab in August 2023.

Story behind the paper. In March-April 2023, I was exploring PyTorch and TensorFlow to understand some simple machine learning algorithms. Then in April 2023, I visited INT Seattle and spoke to participants who were familiar with TRG methods. It appeared to me that they were not aware of the speedup and capabilties of GPU-accelerated tensor contraction schemes for TRG. Abhishek and I realized that we can get a very good speedup of about 10-12x compared to usual CPU tensor computations. I returned to Jefferson Lab and started writing it up. We eventually got it published in Computer Phys. Comm. (CPC). My first and only CPC paper till now!

Story behind the paper. The best way to learn a subject is to teach it. But as a postdoc, you can't always teach. I gave set of lectures at summer school at RPI, Troy and MITP, South Africa, and locally at Hampton University. I decided that I should write them up as it might be useful for some students. I also incorporated some QISKIT programs to allow for more hands-on experience.

Story behind the paper. I had these calculations for a long time. When Anosh asked me to write a short article for EPJ Special Topics, I thought this was a good choice.

Story behind the paper. We (David, Anosh, and I) were working on full bosonic model since 2018. We realized that we could probe the bosonic sector of this model and publish quickly. I found a nic research question that we could conclusively answer -- how does the strong and weak-coupling limits smoothly interpolate. In this paper, we answered this question. Abshishek and Navdeep did most of the numerical simulations for this project. This was also Abhishek's first paper!

Story behind the paper. These proceedings were based on contribution by David at Lattice 2021.

Story behind the paper. In Fall 2020, after working out the details of triad TRG, I was looking for a specific problem that I could answer with this tool. I found that q-state Potts model in 3d were not explored for larger q and location of their phase transitions were unknown. This paper filled this gap. The referees were very negative about the paper. Within three weeks of posting this paper, I was offered my second postdoc and decided that there is no point arguing with referees. This was also the paper that Shinichiro pointed out when we met for the first time.

Story behind the paper. This work started when I was invited to give a set of lectures on a numerical topic at a summer conference organized at Rensselaer Polytechnic Institute. I decided to talk about numerical aspects of matrix models. After a few months, I noticed a new paper on matrix bootstrap by Kazakov and Zheng, arXiv:2108.04830. They applied numerical bootstrap to an unsolved matrix model and claimed several digits of precision for the moments of matrices. Volodya gave a talk at Perimeter, and after the talk, I pulled out my lecture codes, studied this model, and found very good agreement with their results. I showed this to Pedro Vieira, who suggested that it would be nice to check other results in that paper and write an introduction, including all the codes I used, so that future bootstrappers could readily check their results if required. This work was referenced by Kazakov in a Bootstrap Collaboration talk at 1:05:36 , about two weeks before the paper was uploaded on arXiv.

Story behind the paper. These are conference proceedings for the talk at Lattice 2021 at MIT online due to the pandemic.

Story behind the paper. In Fall 2020, when Perimeter was closed due to COVID, Judah and I worked out the details of the triad TRG approach proposed in Fall 2019 by Kadoh et al. Since I had previously explored 2d O(2) model and BKT transition using TRG methods, I thought to apply triad methods to compute critical exponents of 3d O(2) model. I obtained some nice results but was informed by Judah that a group in Germany led by Jacques Bloch was also investigating this problem. We scheduled a Zoom call and started working on this together combining preliminaryresults from me and their group. In particular, we also explored the finite-density limit of the model. However, we could not compute the criticial exponents due to accuracy issues with triad TRG. We revisited this computation in another paper posted in early 2026.

Story behind the paper. My first research paper (Fall 2017) focused on thermodynamics of 1+1-dimensional maximally supersymmetric Yang-Mills theory and its role in gauge/gravity duality. In particular, how the physics of this gauge theory relates to that of D1-branes in some appropriate limit. Already in 2016, we were thinking of extension of this project to consider 2+1-d SYM and how we could compare it to thermodynamics of D2-branes providing non-trivial checks of gauge/gravity duality. This took long time to finish but we pushed it out during COVID.

Story behind the paper. This was Nikhil's paper and idea. I just assisted him and suggested and checked minor details of the paper and assisted in writing. Nikhil and I met in September 2019 at Perimeter when I was a postdoc and he was a PSI Masters student. It was great fun finishing this paper while we were looking of ways to get out of Canada and spent time with family in India during peak COVID. We posted it on arXiv after it was published in Phys.Rev.Res.

Story behind the paper. When I was at Syracuse in Spring 2019, I visited Perimeter to give a talk and Guifre Vidal mentioned to me that TNR might be more effective to probe BKT-type transition. I started working on it using publicly available code at tensors.net written by Glen Evenbly. I reproduced some results but could not fully understand the code. I switched toplain TRG and proceeded by introducing finite symmetry breaking field. It took me sometime to figure out the magnetization accuracy since there was some problem in tensor contraction scheme. I fixed this problem in November 2019 and then gathered results and wrote the paper. This was also my first published single-author paper.

Story behind the paper. These are conference proceedings for the talk at Lattice 2019 which was held in Wuhan, China. Who knew this connection between annual lattice conference and a global pandemic!

Story behind the paper. I obtained these results in November 2019 by using exact form of partition function in terms of determinant of a Toeplitz matrix. This was well-known for U(N) case but I was not aware if it was extended to SU(N). I probed the relation between the 1/N expansion for different observables. Later, I got to know that these results were partially known already, however the numerical results were new to my knowledge. I could not get this published.

Story behind the paper. In Fall 2018, I was trying to start my application for postdoc postions in the US. At the same time, Judah joined the hep-th group at Syracuse and wasworking with Simon. Judah was an expert in tensor renormalization group calculations and we thought to use his expertise and learn a new area (keeping postdoc applications in mind.) Simon involved me in the project and I checked all the calculations which Judah did. We finished comparisons with Monte Carlo methods and eventually finished this paper in January 2019. By the time, I finished this paper, I already had accepted the offer from Perimeter for my first postdoc. Till now this also my highest cited paper. This is because this was the first time someone extended TRG computation to a non-Abelian gauge theory showing improved results compared to Monte Carlo. Memorableone!

Story behind the paper. In Fall 2014, I had to choose between Simon and Jack as my advisor. They both were happy with my performance and could have taken me as their student.I decided that Simon was a better advisor, mentor, and had more dynamic research agenda. I had done lot of work for Jack on Euclidean dynamical triangulations (EDT), however, I was not on any paper with him. This likely would have changed if I had not gone with Simon, who knows! I decided to give a talk in 2018 at Lattice conference and write up my numerical results as a procedings to close this chapter. Now, after a decade of this, I am glad I made the right decision.

Story behind the paper. This paper started in early 2018, when I was thinkling what other projects I can do with the tools I have. At this time, my island of knowledge was restricted, and I could barely see beyond the landscape of lattice SUSY. So, I thought that there might be a nice idea realted to exploring the equation of state of Dp-brane hydrodynamics. I realized that it would take lot of work to write a full paper. So, I decided to present this as a poster at Lattice 2018 at Michigan State University and wrote up the conference proceedings and posted on arXiv.

Story behind the paper. We started this paper following up on what led to a disaster for the paper #. In that paper, we realized we had to change the lattice action to tame the flat directions. However, we realized that at large N, this is mostly harmless and still allows corect supersymmetric continuum behavior. Simon suggested that we write a paper detailing this truncation and its N-effect. Joel and I finished the numerical computations and this paper was out before I was applying for my first postdoc.

Story behind the paper. In February 2017, my advisor Simon asked me to cover him for his invited talk at Yukawa Institute in Kyoto, Japan. At the time he asked me, I had no papers (either published or on arXiv) and I was partially depressed since I was trying my best. So, the challenge was doube. Give a first 45-50 minute invited talk at a string theory/holography conference and without any paper. I did give the talk and did good job. This project started during the questions at the end of the talk. Issaku Kanamori asked me about whether I can probe SUSY breaking in N = (2,2) SUSY in two dimensions. I told him we can likely do it with the lattice formulation we have. After I returned to the US, I started working on this and finished the paper in about 5-6 months. This was my first published work.

Story behind the paper. This manuscript was part of conference proceedings for the annual lattice conference as well. The talk was given by Joel.

Story behind the paper. This manuscript is a conference proceedings for the annual lattice conference that happened in the beautiful city of Granada in Spain. The conference was well-organized and we had great time doing physics and tapas. Another special reason was that I attended this conference traveling with my then one-year old wife.

Story behind the paper. In the summer of 2015 when I was roaming around India meeting friends, I was poised to start my first Phd project. My advisor emailed and asked me to read papers on how one can use lattice super Yang-Mills to probe black holes. In Fall of 2015, I started with the simulations. The computations were challenging (numerically, it is probably the hardest thing I have done yet in my life) and took close to one year to finish around Fall 2016. We had a nice phase space exploration, however, we realized that the action was likely not correct. We then changed the lattice action in Fall 2016. The next round of simulations ended around February 2017. I visited Yukawa Institute in Kyoto in April 2017 and discussed the draft with Toby. We soon realized that we had to still do the mass extrapolations (in order to send one hyperparameter to zero which was added to control the flat directions in lattice SUSY models). Eventually, on September 20, 2017 I posted the paper. This paper had data tables that were 17 pages long. You can still find them on arXiv in ancilliary files.