César Feniou

It turns out that, often, clean workspace qubits can be used in a way that's "viral". Where you end up with more and more workspace that you can use as-if-it-was-clean. Very useful trick, found in parallel by several recent papers. arxiv.org/abs/2407.17966

🚨Important #quantumcomputing results published in @NatureComms today🚨: "Polylogarithmic-depth controlled-NOT gates without ancilla qubits" 👉: doi.org/10.1038/s41467… In quantum computing, multi-control NOT gates are the quantum equivalent of classical ‘AND’ operations. While being true building blocks of quantum algorithms, their decomposition into native quantum gates is non-trivial. In this work, we achieve exponentially shorter circuits than previous state-of-the-art. The resulting exponential speedup is likely to have a substantial impact on fault-tolerant quantum computing by improving the complexities of countless quantum algorithms with applications ranging from quantum chemistry to physics, finance and quantum machine learning. Kudos to @BaptisteClaudon, @ZylbermanJulien, @ChemCesar and nice collaboration with F. Debbasch and @alberto_peruzzo. @LCT_UMR7616 @Sorbonne_Univ_ @CNRSchimie @qubit_pharma Check out also the associated blog on the Nature Physics community: communities.springernature.com/posts/polyloga…

I did my first presentation at the #ACSSpring2024 this morning. It was an incredible opportunity to show my final year PhD projects and connect with fellow researchers. Excited for the discussions and collaborations ahead! Thank you @AmerChemSociety ✨️ #compchem #PhD

And our paper made it to the front Cover of J. Phys. Chem. Lett. @JPhysChem. 𝐒𝐩𝐚𝐫𝐬𝐞 𝐪𝐮𝐚𝐧𝐭𝐮𝐦 𝐬𝐭𝐚𝐭𝐞 𝐩𝐫𝐞𝐩𝐚𝐫𝐚𝐭𝐢𝐨𝐧 𝐟𝐨𝐫 𝐬𝐭𝐫𝐨𝐧𝐠𝐥𝐲 𝐜𝐨𝐫𝐫𝐞𝐥𝐚𝐭𝐞𝐝 𝐬𝐲𝐬𝐭𝐞𝐦𝐬. pubs.acs.org/doi/10.1021/ac… Thanks @ChemCesar and all co-authors. #compchem @LCT_UMR7616 @Sorbonne_Univ_ @CNRSchimie @Genci_fr

#compchem 🚨Just out in J. Phys. Chem. Lett @JPhysChem 🚨and incoming Front Cover: 𝐒𝐩𝐚𝐫𝐬𝐞 𝐪𝐮𝐚𝐧𝐭𝐮𝐦 𝐬𝐭𝐚𝐭𝐞 𝐩𝐫𝐞𝐩𝐚𝐫𝐚𝐭𝐢𝐨𝐧 𝐟𝐨𝐫 𝐬𝐭𝐫𝐨𝐧𝐠𝐥𝐲 𝐜𝐨𝐫𝐫𝐞𝐥𝐚𝐭𝐞𝐝 𝐬𝐲𝐬𝐭𝐞𝐦𝐬. doi.org/10.1021/acs.jp… First peer-reviewed paper using our #GPU-accelerated Hyperion-1 quantum computer emulator. This work presents extensive 28 logical qubits simulations performed on a single @nvidia (8 X A100 GPU) #HPC node. We conducted quantum state preparation for complex molecular systems using various advanced methods that are evaluated and compared in terms of their circuit depth, CNOT count & classical computational complexity. Our simulations indicate that the recently developed Overlap-ADAPT-VQE algorithm (Commun Phys, 2023, 6, 192) offers the most advantageous performance for near-term applications. Congrats @ChemCesar @qubit_pharma! Nice collaboration with E. Giner @LCT_UMR7616. Supercomputer time @Genci_fr.

@CraigGidney Any thoughts on thm1? it seems to me that the given C...CX is only O(n) depth and not O(logn) (possibly due to a missing pre-factor in the depth recursion). A polylog decomposition with similar construction was previously given in arxiv.org/abs/2312.13206

arxiv.org/abs/2402.05053 proves exactly making C..CX without ancillas needs ever-more-precise gates. Adding a qubit turns the determinant e^(iτA/B) into e^(iτ2A/B). This eventually forces B odd and A even for all gates. No product of such dets can make e^(iτ/2), the det of C..CX.

New #preprint between our group @LCT_UMR7616 and @qubit_pharma : Polylogarithmic-depth controlled-NOT gates without ancilla qubits. arxiv.org/abs/2312.13206 The question of decomposing efficiently any n-qubit operation into a reasonable number of primitive single- and two-qubit operations is one of the major challenges in #quantumcomputing. In this context, multi-controlled operations (n-Toffoli gates) act as building-blocks of many prevalent quantum algorithms. For this reason, achieving more effective decompositions of multi-controlled operations has the potential to bring about significant enhancements in quantum algorithms. We propose a complete strategy to obtain an exponential speedup for these tasks. It is likely that such results will have a substantial impact on fault-tolerant quantum computing (#FTQC) by improving the complexities of countless quantum algorithms including key #compchem ones. Stellar work from Baptiste Claudon, @julienzylberman and @ChemCesar. Great collaboration with F. Debbasch and @alberto_peruzzo. @Sorbonne_Univ_ @CNRS

#compchem New #quantumcomputing preprint: Sparse quantum state preparation for strongly correlated systems. Check it out here: arxiv.org/abs/2311.03347 We conducted quantum state preparation for complex molecular systems using various advanced methods that are evaluated and compared in terms of their circuit depth, CNOT count & classical computational complexity. Our simulations indicate that the recently developed Overlap-ADAPT-VQE algorithm (Commun Phys, 2023, 6, 192) offers the most advantageous performance for near-term applications. Our findings are supported by computations up to 28 qubits thanks to our in-house (multi)GPU-accelerated state-vector emulator => 28 qubits on a single @nvidia DGX-A100 !!! Great work by @ChemCesar and another nice collaboration between the @piquemalgroup (@LCT_UMR7616 ) and @qubit_pharma. @OlivierApp Emmanuel Giner

Quantum computers are likely to outperform classical devices on a range of chemical simulations. This front page highlighted paper by @jppiquem and collaborators explores with creating compact ansatz wave-functions while achieving chemical accuracy. nature.com/articles/s4200…

Overlap-ADAPT-VQE: practical quantum chemistry on quantum computers via overlap-guided compact Ansätze nature.com/articles/s4200…

You can also read our associated ”Behind the Paper” contribution on the @Nature Portfolio Physics Blog Community page : physicscommunity.nature.com/posts/practica…

Interested by compact ansätze to perform quantum chemistry computations on #QuantumComputing devices? Read our paper @CommsPhys🔥🔥. Shout out to the amazing César Feniou @ChemCesar & Mohammad Hassan. Great #compchem/#mathematics collab. with Yvon Maday. nature.com/articles/s4200…

Huge work by @ChemCesar and great collaboration with Y. Maday's group (LJLL @Sorbonne_Univ_ ). Funded in part @ERC_Research (project EMC2). A big thank to @awscloud (Braket) for support. @LCT_UMR7616 @qubit_pharma

#QuantumComputing #compchem #HPC #supercomputing New group #preprint: Greedy Gradient-free Adaptive Variational Quantum Algorithms on a Noisy Intermediate Scale Quantum Computer. arxiv.org/abs/2306.17159

@theoboutdmabite @WissalGwissal Ok je m'en occupe ce soir

@ChemCesar @WissalGwissal j’aurais besoin de l’analyse RMN j’ai plusieurs questions, fait le quand t’as le temps je suis pas pressé aha et merci d’avance

est ce que y a des gens chauds en chimie par ici?

@theoboutdmabite @WissalGwissal Envoie le moi si besoin ;)

@WissalGwissal Olympiades internationales de chimie donc niveau ENS selon mes profs mais l’exo est pas du tout dur, faut juste avoir des notions de RMN pour la question que j’ai