The Quantum Paper Club is organized by students for students. Its goal is to expose the students interested in Quantum Engineering to the research done in the field. More than this, it is a formidable platform to practice public scientific speaking.
The Quantum Paper Club usually takes place on Thursdays at 17:45 in HIT H42. If you would like to present, please contact Kai Gamlin () or Lisa Peters ().
Next Talk
07.03.2024
17:45
ETH Hönggerberg, HIT H 42
07.03.2024
17:45
ETH Hönggerberg, HIT H 42

Twodimensional terahertz spectroscopy in complex matter systems
07.03.2024Alex Gomez Salvador
Twodimensional terahertz spectroscopy (2DTS), a terahertz analogue of nuclear magnetic resonance, stands as a novel technique poised to address numerous open questions in complex condensed matter systems. The conventional theoretical framework, widely used for interpreting multidimensional spectra of discrete quantumlevel systems, falls short in capturing the continua of collective excitations in strongly correlated materials, and…
Past Talks

Single Molecular Ions for Precision Spectroscopy and Molecular Quantum Technologies
29.02.2024Richard Karl
Within the rich energy level structure of molecules, transitions with advantageous properties for precision studies and molecular quantum technologies can be found [1]. However, in the absence of closed cycling transitions and frequencies ranging from MHz for hyperfine transitions to GHz in rotational transitions and THz in rovibrational transitions [2], efficient cooling of translational degrees…

MultiQubit Gates for Bosonic Logical Qubits
22.02.2024Ivan Rojkov
Bosonic codes comprise a paradigm for quantum computing and quantum error correction where quantum information is encoded in continuous degrees of freedom such as modes of radiation or motion. In particular, GottesmanKitaevPreskill (GKP) codes [1] are promising candidates for bosonic quantum information processing, in which quantum error correction has recently been demonstrated both in superconducting…

Quantum Control of a CatQubit With BitFlip Times Exceeding Ten Seconds
14.12.2023Dr. Ronan Gautier
Cat qubits encode quantum information in the metastable states of a quantum harmonic oscillator, offering robust protection to bitflip errors. This talk presents a cat qubit with bitflip durations over ten seconds, greatly surpassing both previous implementations of the qubit and the lifetime of its components. This is achieved through a new quantum tomography method…

Precision Spectroscopy in the Helium Atom
07.12.2023Gloria Clausen
Few electron atoms and molecules such as H, He(+), H2(+) and He2(+) are simple enough for their properties to be calculated exactly from first principles (QM, QED). Comparison with precisionspectroscopic data enables one to test the calculations, reduce the uncertainties of fundamental constants and determine particle properties (e.g. α, mp/me and RH) or may allow…

Cryptography and Quantum Key Distribution
30.11.2023Riccardo Cicchetti
Faulttolerant Quantum Computers threaten the current cryptographic mechanisms on which the security of our daytoday communication relies. Extensive research is conducted to find, socalled, PostQuantum cryptographic primitives. In other words, cryptographic tools that should be hard to break for a quantum computer at scale. However, the security of these solutions is still reliant on a…

Practical Quantum Algorithms
23.11.2023Guglielmo Mazzola
In this talk, I will delve into obvious, less obvious, and subtle challenges, as well as good practices for developing quantum algorithms in pursuit of practical quantum advantage. This is defined as achieving a quantum algorithm faster than the best possible classical algorithm for a genuinely relevant problem in science and technology. I will place…

Quantum Causal Models
16.11.2023Carla Ferradini
Inferring cause and effect relations from observed correlations is a fundamental aspect of science. A causal modelling framework has been formulated to describe correlations among classical random variables arising from a causal structure and has found diverse applications in machine learning, economics, and clinical trials. However, experimental violations of Bell inequalities demonstrate the inadequacy of…

Developing Superconducting Bosonic Qubits in a Planar LowLoss Architecture
09.11.2023Alessandro Bruno
Emerging quantum technologies, including quantum computers and quantum simulators, crucially rely on highquality qubits. However, even stateoftheart qubits are susceptible to errors caused by noise processes, which impose constraints on the device performance. Standard approaches to quantum error correction aim to suppress these errors by introducing redundancy based on coupling a large number of qubits,…

Performance Constraints of NISQ Quantum Algorithms and their Mitigation with 3DIntegrated Superconducting Quantum Devices
26.10.2023Kieran Dalton
In recent years, the excitement around NISQ algorithms has diminished, partly due to the performance limitations of existing quantum computers. Devices with more qubits and lower error rates are necessary to realize the potential of quantum computing. In the first half of this talk, I will illustrate these performance limitations with the example of the…

Quantum Imaging of Nanoscale Electronic Transport in Graphene with NitrogenVacancy Centers in Diamond
19.10.2023Chaoxin Ding
Nitrogenvacancy (NV) center in diamond, a spin qubit with long coherence time up to room temperature, has been demonstrated as a powerful tool for various quantum technologies, especially for quantum sensing. In this presentation, I will show its promising application for investigating nanoscale electronic transport phenomena in condensed matter physics, specifically, hydrodynamic flow in graphene.…

Spin and MomentumCorrelated Atom Pairs via Photon Exchange and Vacuum Fluctuations
12.10.2023Fabian Finger
Mechanisms generating correlated pairs of particles are at the core of diverse fields of physics such as Hawking radiation, phononmediated superconductivity or spontaneous parametric downconversion. Similar approaches have been explored with ultracold atoms to correlate massive particles in various degrees of freedom. We use a BoseEinstein condensate coupled to a highfinesse optical cavity to generate…

Integrated Optics for Scalable TrappedIon Quantum Computing
05.10.2023Gillenhaal Beck
Trapped ions provide a promising platform for large scale quantum computing. A crucial element of this scalability will be the integration of laser light into the trapping chips themselves. In this talk, I will first provide a brief overview of trappedion systems and the path to scalability. The many benefits provided by integrated photonics will…

Photonics Building Blocks in Alumina for Controlling Trapped Ions
28.09.2023Sophie Cavallini
Photonic integrated circuits (PIC) can be exploited to control trapped ions more robustly than freespace optics. Most of the work done in this area used silicon nitride (Si3N4), however, it is incompatible with UV wavelengths. Instead, aluminium oxide (Al2O3) proves to be a suitable waveguide material. This project focuses on designing and optimizing several integrated…

SinglePhotons, Entangled Photon Pairs & Optimal Quantum Cloning of Qubits
25.05.2023Nicolas Gisin
Quantum physics has many applications today, many techniques have been developed and are now used in various fields. However, going back to the foundations, there are many interesting and still unresolved questions. This week, Nicolas Gisin will talk about the single photon, how to define it and how far it can travel if you want…

Atomistic DFT Simulation of Scaled 3nm FinFET & 22nm FDSOI CMOS Quantum Dot Devices
17.05.2023Vivek Dhande
Current production FinFET and FDSOI CMOS technologies are suitable for largescale, highdensity quantum processor (QP) and readout control electronics. Due to layout manufacturability restrictions, that limit the types of qubit arrays and gates that can be implemented, the top gate pitch is too large for strong tunnel coupling between adjacent quantum dots (QDs), limiting the…

A Quantum Information View on Black Holes
11.05.2023Giulia Mazzola
A major discovery by Hawking was that the interplay between general relativity and quantum theory leads to the prediction that black holes must radiate. In Hawking’s original calculation however, the black hole radiation was found to be of thermal character, thus leaving behind a mixed state describing the radiation as soon as the black hole…

Schrödinger Cat States in a 16microgram Mechanical Oscillator
04.05.2023Marius Bild
While the principle of superposition in quantum physics is routinely validated for microscopic systems, it is still unclear why we do not observe macroscopic objects to be in superpositions of states that can be distinguished by some classical property. I will present our experiments, that harness the resonant JaynesCummings interaction between a high overtone resonator…

Motional Squeezing for Trapped Ion Transport and Separation
27.04.2023Dario Scheiwiller
One of the (many) challenges in scalable quantum computing with trapped ions is the transport of the ions. The transport of the ions needs to be done while avoiding the archenemy of iontrappers: motional heating. In my talk we’ll discuss a recent paper by Sutherland et al. that explores a new protocol of ion transport,…

From Machine Learning to Computational Quantum Physics
06.04.2023Filippo Vicentini
Machinelearning techniques that originated in several domains of “Artificial Intelligence”, are increasingly being applied to tackle problems in physical sciences. Applications range from experimental fields, where ML has been leveraged to more efficiently carry out measurements, inhibit noise or design structures, to computational and theoretical physics. In particular, a recent breakthrough showed that several numerical…

Quantum Control of Trapped Ions with Integrated Photonics
30.03.2023Alfredo Ricci Vásquez
Scaling up trapped ion quantum information processors requires high fidelity control over many ions. One way of achieving such control is by using a trap with multiple zones, each zone holding few ions which can be manipulated with high fidelity. Operations between the ions are achieved by means of transporting the ions across zones. Although…

Realizing Quantum Convolutional Neural Networks on a Superconducting Quantum Processor to Recognize Quantum Phases
23.03.2023Johannes Herrmann
Quantum computing crucially relies on the ability to efficiently characterize the quantum states output by quantum hardware. Conventional methods which probe these states through direct measurements and classically computed correlations become computationally expensive when increasing the system size. Quantum neural networks tailored to recognize specific features of quantum states by combining unitary operations, measurements and…

An Intuitive Approach to Analogue Gravity in BoseEinstein Condensates
16.03.2023Sébastien Garmier
An analogue gravity model is a physical system in flat spacetime with wave propagation behaving like the propagation of a scalar field of mass m in some curved spacetime. In the first part, we review analogue gravity models with wave propagation governed by a Lagrangian. In this context we propose a novel and more pedagogical…

Quantum Knitting for Dummies
09.03.2023James O’Sullivan
Multidimensional tensornetwork states, such as cluster states, are a key resource for quantum communication and measurementbased quantum computing. Recently, cluster states have been generated both in the microwave and optical regime but the generation of largescale 2D cluster states in discretevariable systems remains challenging. We present a superconducting device to enable the generation of twodimensional…

Quantum Computing Applications and the Measurement Problem
02.03.2023Laurin Fischer
With digital quantum computers reaching the scale of ~100 qubits and everincreasing gate fidelities and coherence times, potential applications of quantum computing can now be explored on noisy hardware. This talk gives an overview of such applications with a particular focus on algorithms for quantum chemistry. On noisy hardware, i.e., before faulttolerance, the depth of…
Meeting date  Topic  Presenter  Abstract  Link to reference 

26.04.2022  The impact of quantum mechanics on philosophy  Lev Vaidman (Professor @ Tel Aviv University)  The uncertainty principle and Belltype correlations led to a dramatic change in the philosophy of science. Today we are ready to accept indeterminism and some kind of action at a distance. I will argue that this move is not necessary and maybe mistaken. Accepting the existence of multiple parallel worlds allows restoring determinism and avoiding action at a distance. The issue of probability in the manyworlds framework, however, requires introducing a novel element in science. Warning: I plan to split the world during the talk!  
19.04.2022  Dynamic generation of entangled electrons in a Cooper pair splitter  Fredrik Brange (PostDoc @ Aalto University)  Cooper pair splitters are promising candidates for generating spinentangled electrons. However, the splitting of Cooper pairs is a random and noisy process, which hinders further synchronized operations on the entangled electrons. To circumvent this problem, we propose and analyze a dynamic Cooper pair splitter that produces a noiseless and regular flow of spinentangled electrons. The Cooper pair splitter is based on a superconductor coupled to quantum dots, whose energy levels are tuned in and out of resonance to control the splitting process. We identify the optimal operating conditions for which exactly one Cooper pair is split per period of the external drive and the flow of entangled electrons becomes noiseless. To characterize the regularity of the Cooper pair splitter in the time domain, we analyze the g(2) function of the output currents and the distribution of waiting times between split Cooper pairs. Our proposal is feasible using current technology, and it paves the way for dynamic quantum information processing with spinentangled electrons.  Link 
12.04.2022  Introduction to dissipation engineering  Elias Zapusek (PhD @ ETH TIQI)  Dissipation arises in quantum systems due to interaction with environment. In unitary quantum information processing dissipation is primarily considered as a source of noise. However, we can also use controlled dissipation to manipulate quantum systems. Starting from the most wellknown example optical pumping and moving on to more complex schemes I will give a brief introduction to the field of dissipation engineering.  Link 
05.04.2022  Saving the cat: From open quantum systems to bosonic quantum error correction  David Schlegel (PhD @ EPFL)  A popular approach for realizing a faulttolerant quantum computer is to construct logical qubits encoded in multiple physical twolevel qubits. Recent alternative approaches are based on bosonic quantum codes which are quantum error correcting (QEC) codes that redundantly encode quantum information in the states of a quantum harmonic oscillator, making it possible to detect and correct errors, while reducing the hardware resource overhead. In this talk, I will provide an overview of QEC in bosonic systems and review various bosonic quantum codes such as GKP and cat codes. Furthermore, I will show recent results on a novel bosonic quantum code, called the squeezed cat code, that enables to correct both dephasing and loss errors. We show that with moderate squeezing, and using typical parameters of stateoftheart quantum hardware platforms, the squeezed cat code has a resilience to loss errors and dephasing errors that significantly outperform that of the conventional cat code.  Link 
29.03.2022  HardwareTailored Diagonalization Circuits  Daniel Miller (PhD @ IBM)  A central building block of many quantum algorithms is the diagonalization of Pauli operators. Although it is always possible to construct a quantum circuit that simultaneously diagonalizes a given set of commuting Pauli operators, only resourceefficient circuits are reliably executable on nearterm quantum computers. Generic diagonalization circuits can lead to an unaffordable Swapgate overhead on quantum devices with limited hardware connectivity. A common alternative is excluding twoqubit gates, however, this comes at the cost of restricting the class of diagonalizable sets of Pauli operators to tensor product bases (TPBs). In this letter, we introduce a theoretical framework for constructing hardwaretailored (HT) diagonalization circuits. We apply our framework to group the Pauli operators occurring in the decomposition of a given Hamiltonian into jointlyHTdiagonalizable sets. We investigate several classes of popular Hamiltonians and observe that our approach requires a smaller number of measurements than conventional TPB approaches. Finally, we experimentally demonstrate the practical applicability of our technique, which showcases the great potential of our circuits for nearterm quantum computing.  Link 
22.03.2022  PhotonPair generation from single LiNbO3 microcubes and GaAs nanowires  Saerens Grégoire (PhD @ ETH)  Nonclassical light sources are highly sought after as they are an integral part of quantum communication and quantum computation devices. Typical sources rely on bulk crystals that are not compact and have limited bandwidth due to phasematching conditions. Here I will present generation of photon pairs at the telecommunication wavelength from freestanding LiNbO 3 microcubes and freestanding GaAs cut Nanowires using the spontaneous parametric down conversion process. I will show the fabrication process for each of this nanostructure, the setup configuration for free space spontaneous parametric downconversion, as well as the alignment challenges when trying to observe this wavelength conversion process in transmission. We will compare experimental as well as simulation results for both nanostructures.  Link 
15.03.2022  No session – Pauli Lectures  
08.03.2022  Quantum Memories in a Quantum Network  Moritz Businger (PhD @ UNIGE)  Quantum memories are one of the corner stones in a quantum network. It enables communication beyond the loss limit of direct communication and lets us use more complex protocols for quantum computation. Here I will present the ensemble based quantum memory approach we are perusing in Geneva and show how this lets us store a record number of quantum states in a rare earth ion doped crystal. Especially our recent work on Ytterbium is very competitive in terms of capacity and storage time which makes it a perfect candidate implementation in a largescale quantum network.  
01.03.2022  Blueprint for a Scalable Photonic FaultTolerant Quantum Computer  Ilan Tzitrin and Eli Bourassa (Xanadu)  Link  
14.12.2021  Realizing Repeated Quantum Error Correction in a DistanceThree Surface Code  Nathan Lacroix (PhD @ Qudev, ETH)  Link  
07.11.2021  Joint measurability of binary qubit measurements  Dmitry Grinko (PhD @ U. o. Amsterdam)  
30.11.2021  An addressable quantum dot qubit with faulttolerant controlfidelity  Markus Niese  Link  
23.11.2021  Universal quantum computation with ideal Clifford gates and noisy ancillas  Ivan Rojkov (PhD @ TIQI, ETH)  Link  
16.11.2021  Frequencydomain HongOuMandel interference  Dario Scheiwiller  Link  
09.11.2021  Strong Optomechanical Coupling at Room Temperature  Dr. Nadine Meyer (Senior Scientist @ NSL, ETH)  —  
02.11.2021  Measurement of Subpicosecond Time Intervals between Two Photons by Interference  Moritz Fontboté Schmidt  Link  
26.10.2021  Test of the Local Realism and Realism in Particle Physics  Anna Efimova  Link  
21.10.2021  Stabilization and operation of a Kerrcat qubit in a nonlinear superconducting resonator  Dr. Alexander Grimm (PSI)  Link  
14.10.2021  Error correction with realtime Feedback for Surface 17 on the Zurich Instruments setup  Liberto Beltrán  
07.10.2021  Demonstrating the power of stateoftheart quantum computers  Elisa Bäumer (PhD @ Renner/ETH+IBM)  
01.07.2021  Bulk crystalline optomechanics  Elisa Bäumer (PhD @ Renner/ETH+IBM)  Link  
24.06.2021  Constructing quantum codes from any classical code and their embedding in ground space of local Hamiltonians  Dina Abdelhadi, (PhD @ EPFL)  Link  
17.06.2021  Controlling the competition between coherent and dissipative processes in a superradiant quantum gas.  Francesco Ferri (Postdoc @ Esslinger/ETH)  Link  
10.06.21  Strawberry Fields: A Software Platform for Photonic Quantum Computing  Ivan Rojkov/Moritz Fontboté Schmidt  Link  
03.06.2021  A gatetunable, fieldcompatible fluxonium  Marta Pita Vidal (TU Delft)  Link  
27.05.2021  Qiskit Pulse: Programming Quantum Computers Through the Cloud with Pulses  Caroline Tornow  Link  
20.05.2021  Quantum Architecture Search via Deep Reinforcement Learning  Kristina Kirova  Link  
13.05.2021  Generation of Nonclassical Motional States of a Trapped Atom  Moritz Fontboté Schmidt  Link  
06.05.2021  Quantum acoustics with superconducting qubits  Alessandro Bruno  Link  
29.04.2021  Chiral Quantum Optics  Chaoxin Ding  Link  
15.04.2021  Quantum error correction of a qubit encoded in grid states of an oscillator  Alec Eickbusch (PhD student at Prof. Devoret’s Qulab at Yale University)  Link  
01.04.2021  A fourqubit germanium quantum processor  Ivan Rojkov  Link  
25.03.2021  Predicting many properties of a quantum system from very few measurements  Ivan Rojkov  Link  
18.03.2021  A networkready randomaccess qubits memory  Stefano Marti  Link  
11.03.2021  How to put quantum particles on magic bullet trajectories that can hit two targets without a clear lineofsight  Ivan Rojkov  Link  
02.03.2021  SpinQ Gemini: a desktop quantum computer for education and research  Moritz Fontboté Schmidt  Link  
23.02.2021  Strongly correlated Fermions strongly coupled to light  Prof. JeanPhilippe Brantut (EPFL)  Laboratory for Quantum Gases  
08.12.2020  Error correction of a logical grid state qubit by dissipative pumping  Ivan Rojkov & Moritz Fontboté Schmidt  Link  
1.12.2020  Observation of coherent optical information storage in anatomic medium using halted light pulses  Moritz Fontboté Schmidt  Link  
24.11.2020  Quantum memories for photons  Dr. Mikael Afzelius  Quantum Repeaters & Memories  
17.11.2020  Measurement of subpicosecond time intervals between two photons by interference  Moritz Fontboté Schmidt  Link  
10.11.2020  Quantumdot spin–photon entanglement via frequency downconversion to telecom wavelength  Marco Stucki  Link  
03.11.2020  Observation of entanglement between a quantum dot spin and a single photon  Chaoxin Ding  Link  
27.10.2020  An introduction to Pound–Drever–Hall laser frequency stabilization  Moritz Fontbote Schmidt & Benjamin van Ommen  Link  
20.10.2020  Cavity Quantum Electrodynamics at Arbitrary LightMatter Coupling Strengths  Alperen Tügen  Link  
13.10.2020  Architecture for a largescale iontrapquantum computer  Ivan Rojkov  Link  
06.10.2020  Interactionassisted reversal of thermopower with ultracold atoms  Moritz Fontbote Schmidt  Link  
29.09.2020  Charge Insensitive Qubit Design derived from the Cooper Pair Box  Moritz Fontbote Schmidt  Link  
22.09.2020  HartreeFock on a superconducting qubit quantum computer  Ivan Rojkov  Link  
21.07.2020  Generation of entangled photon states in optical downconversion and upconversion processes.  Sahnawaz Alam (MSc in Physics at Indian Institute of Technology Gandhinagar)  
07.07.2020  From nanotech to living sensors:unraveling the spin physics of biosensing at the nanoscale  Prof. Clarice D. Aiello (Assistant professor at UCLA and head of the Quantum Biology Tech (QuBiT) Lab )  
30.06.2020  Direct Measurement of the Density Matrix of a Quantum System  Alperen Tügen  Paper  
23.06.2020  Proofofconcept proposal for machine learning using superconducting qubits (Master Thesis)  Colin Scarato  Contact speaker  
16.06.2020  NormalMode Splitting in a Weakly Coupled Optomechanical System  Francesco Adinolfi  Paper  
09.06.2020  Optimal cooling of a spinboson system  Emanuel Malvetti (Semester thesis)  Contact speaker  
02.06.2020  Direct measurement of the Zak phase in topological Bloch bands  Benjamin van Ommen  Paper  
26.05.2020  Ramsey interferometry with dissipative quantum error correction  Ivan Rojkov (Semester thesis)  Contact speaker  
19.05.2020  CavityBased 3D Cooling of a Levitated Nanoparticle via Coherent Scattering  Dominik Windey (Phd Student in the Novotny/Photonics group)  Paper, PDF of presentation  
12.05.2020  Integrated optical multiion quantum logic  Chi Zhang (PhD student in the Home/TIQIgroup)  Paper  
05.05.2020  Topological Quantum Computing  Oriel Kiss  Lecture notes by Preskill  
28.04.2020  Remote quantum entanglement between two micromechanical oscillators  Marco Stucki  Paper  
21.04.2020  Nonclassical correlations between single photons and phonons from a mechanical oscillator  Chaoxin Ding  Paper  
15.04.2020  Reinforcement Learning in Different Phases of Quantum Control  Pedro Rosso  Paper  
08.04.2020  CavityAssisted Quantum Bath Engineering  Moritz Fontboté Schmidt  Paper  
1.04.2020  Errormitigated quantum gates exceeding physical fidelities in a trappedion system  Moritz Fontboté Schmidt  Paper  
(Coronabreak)  
10.03.2020  To catch and reverse a quantum jump mid flight  Alperen Tugen  Paper  
02.03.2020  Entanglement of two quantum memories via fibres over dozens of kilometres  Moritz Fontboté Schmidt  Paper  
25.02.2020  Atombyatom assembly of defectfree onedimensional cold atom arrays  Yongxin Song  Paper  
18.02.2020  Fast twoqubit logic with holes in Germanium  Moritz Fontboté Schmidt  Paper  
17.12.19  How often should you beat your kids?  Moritz Fontboté Schmidt  Paper  
10.12.2019  SingleShot Quantum Nondemolition Detection of Individual Itinerant Microwave Photons  Moritz Fontboté Schmidt  Paper  
03.12.2019  Universal Gate for FixedFrequency Qubits via a Tunable Bus  Moritz Fontboté Schmidt  Paper  
26.11.2019  Ultracold and unreactive fermionic molucules and A degenerate Fermi gas of polar Molecules  Marit Fiechter  Paper and Paper  
19.11.2019  Measurement of subpicosecond time intervals between two photons by interference  Moritz Fontboté Schmidt  Paper  
12.11.2019  Towards faulttolerant quantum computing with trapped ions  Moritz Fontboté Schmidt  Paper  
05.11.2019  Quantum Computations with Cold Trapped Ions  Moritz Fontboté Schmidt  Paper  
29.10.2019  Nanoscale imaging magnetometry with diamond spins under ambient conditions  Alperen Tügen, Moritz Fontboté Schmidt  Paper  
22.10.2019  Charge Insensitive qubit design derived from the cooper pair box  Benjamin Van Ommen, Alperen Tugen, Moritz Fontboté Schmidt  Paper 
If not noted otherwise, presenters were ETH students.