The seminar is organized via LV0622

Content

This is the joint module page of LV0622 "Supraleitende Quantenschaltkreise" and LV1569 "Cavity-, Circuit- und Waveguide-QED".

Within the seminars, students present state-of-the-art developments in modern quantum technology with superconducting quantum circuits. In this field, funamental research in academia has meanwhile triggered highly dynamical activities from established large corporations (Google, IBM, Intel etc.) and ambitious startups (Rigetti, IQM, HQS etc.). In particular, superconducting quantum circuits belong to the few prime candidates for a scalable quantum computer.

Time/Place

The seminar will take place on Tuesdays 12:15 - 14:00h, WMI-Seminarroom 143

Schedule

Below, you will find a list of papers we picked for the seminar. Please have a look, identify a paper that interests you and let me know which one you would like to present in the seminar until the first of November. 

You will be put in contact with a tutor, that will help you in preparing the slides for your presentation. Typically, you will have one or two sessions with your tutor.  

We will organize a schedule for the seminar talks, and I would ask you to keep the timeslot of the seminar free, and also join the presentations of your peers. Until the schedule is released, the seminar will not take place! After release, we will follow the schedule. 

Your seminar talk should be about 30 minutes long, with 10-15 minutes of scientific discussion afterwards. 

List of open topics for seminar talks in WS2025:
Please pick a topic related to your seminar - ie. theory for LV1569 and quantum computing, quantum sensing or hybrid systems for LV0622

Quantum Computing:

1. Logical quantum processor based on reconfigurable atom arrays (Nature, Lukin (Hrvard/MIT)),
   https://www.nature.com/articles/s41586-023-06927-3
2. Combining quantum processors with real-time classical communication (Nature,  IBM),
   https://www.nature.com/articles/s41586-024-08178-2
3. Realizing Lattice Surgery on Two Distance-Three Repetition Codes with Superconducting Qubits (Arxiv, Wallraff)
   https://arxiv.org/abs/2501.04612
4. Deterministic remote entanglement using a chiral quantum interconnect (Nature, Oliver (MIT))
   https://doi.org/10.1038/s41567-025-02811-1
5. Hardware efficient quantum error correction via concatenated bosonic qubits (Nature, Painter)
   https://www.nature.com/articles/s41586-025-08642-7
6. Quantum error detection in qubit-resonator star architecture  (arxiv, Deppe (IQM))
   https://doi.org/10.48550/arXiv.2503.12869
7. Quasiparticle poisoning of superconducting qubits with active gamma irradiation (Arxiv, Plourde)
   https://doi.org/10.48550/arXiv.2503.0735
8. Quantum control of a cat qubit with bit-flip times exceeding ten seconds (Leghtas),
   https://arxiv.org/pdf/2307.06617
9. Full Characterization of Genuine 17-qubit Entanglement on the Superconducting Processor (PRL, Yu)
   https://journals.aps.org/prl/abstract/10.1103/qy9y-7ywp
10. Dual-rail encoding with superconducting cavities (Schoelkopf, Yale),
    https://www.pnas.org/doi/abs/10.1073/pnas.2221736120
11. Single-Qubit Gates with Errors at the 10−7 Level (PRL, Lucas)
    https://journals.aps.org/prl/abstract/10.1103/42w2-6ccy
12. Benchmarking the Readout of a Superconducting Qubit for Repeated Measurements (PRL, Devoret) 
    https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.134.100601
13. Scaling and logic in the colour code on a superconducting quantum processor(nature, Google)
    https://www.nature.com/articles/s41586-025-09061-4
14. Quasiparticle Poisoning of Superconducting Qubits with Active Gamma Irradiation­ (PRX Quantum, Plourde)
    https://journals.aps.org/prxquantum/abstract/10.1103/2lyd-8swv
15. Fast Multiplexed Superconducting-Qubit Readout with Intrinsic Purcell Filtering Using a Multiconductor Transmission Line (PRX Quantum, Nakamura)
    https://journals.aps.org/prxquantum/abstract/10.1103/PRXQuantum.6.020345
16. Cryogenic microwave link for quantum local area networks (npj QI, Fedorov)
    https://www.nature.com/articles/s41534-025-01046-5

Quantum Sensing

1. Correlation Spectroscopy with Multiqubit-Enhanced Phase Estimation (Roos, Blatt , Innsbruck),
   https://journals.aps.org/prx/abstract/10.1103/PhysRevX.14.011033
2. High-sensitivity AC-charge detection with a MHz-frequency fluxonium qubit (Deleglise, CNRS),
   https://journals.aps.org/prx/abstract/10.1103/PhysRevX.14.011007
3. Quantum advantage in microwave quantum radar (Huard, Lyon),
   https://doi.org/10.1038/s41567-023-02113-4

Hybrid Quantum Systems

1. Quantum-enabled millimetre wave to optical transduction using neutral atoms (Schuster, Simon, Stanford),
   https://www.nature.com/articles/s41586-023-05740-2
2. Single electron-spin-resonance detection by microwave photon counting (Flurin, Bertet, CEA Saclay),
   https://www.nature.com/articles/s41586-023-06097-2

Research papers with focus on theory:

Superinductance:

• Symmetries and Collective Excitations in Large Superconducting Circuits (Koch, Northwestern),
  https://doi.org/10.1103/PhysRevX.3.011003
  Supplemental material:
  - Experiments: Microwave characterization of Josephson junction arrays: implementing a low loss superinductance (Devoret, Yale), https://doi.org/10.1103/PhysRevLett.109.137002
  - Supplemental theory: Consistent Quantization of Nearly Singular Superconducting Circuits (DiVincenzo, RWTH), https://doi.org/10.1103/PhysRevX.13.021017

State preparation in Open Quantum Systems:

• Accelerating Dissipative State Preparation with Adaptive Open Quantum Dynamics (Clerk, Chicago), https://doi.org/10.1103/PhysRevLett.134.050603

Couplers:

• Balanced coupling in electromagnetic circuits (Atalaya, Google),
  https://doi.org/10.1103/PhysRevApplied.23.024012
  Supplemental material:
  - Experimental realization: Suppressing Counter-Rotating Errors for Fast Single-Qubit Gates with Fluxonium (Oliver, MIT), https://doi.org/10.1103/PRXQuantum.5.040342

New Qubits:

• Dissipative cats: Enhancing dissipative cat qubit protection by squeezing (Murani,A&B),
  https://doi.org/10.48550/arXiv.2502.07892

Driven dissipative systems:

1. Inducing Nonclassical Lasing via Periodic Drivings in Circuit Quantum Electrodynamics (Porras, CSIC),
   https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.113.193601
2. Waveguide QED with dissipative light-matter couplings (Nori, RIKEN),
   https://journals.aps.org/prresearch/abstract/10.1103/PhysRevResearch.7.L012036

Many-body quantum optics:

1. Deterministic generation of photonic entangled states using decoherence-free subspaces (Asenjo-Garcia, Columbia),
   https://arxiv.org/abs/2410.03325
2. Universal scaling laws for correlated decay of many-body quantum systems (Asenjo-Garcia, Columbia),
   https://arxiv.org/abs/2406.00722

Non-Markovian waveguide QED: 

• Multimode-cavity picture of non-Markovian waveguide QED (Ciccarello, Palermo)
  https://arxiv.org/abs/2403.07110

Remote entanglement

• Loss resilience of driven-dissipative remote entanglement in chiral waveguide quantum electrodynamics
  https://journals.aps.org/prresearch/abstract/10.1103/PhysRevResearch.6.033212

Input-Output theory

• Path Integral Approach to Input-Output Theory
  https://arxiv.org/abs/2509.07563

Quantum Communication

• Robust quantum communication through lossy microwave links
  https://arxiv.org/abs/2509.18547

Topical directions of the seminar:

• Foundations and applications of superconducting quantum circuits in quantum computing, quantum simulation, quantum communication, quantum sensing, and quantum metrology.
• Superconducting quantum technology: Resonators, waveguides, quantum bits, couplers, quantum-limited amplifiers, quantum processors, quantum error correction etc.
• State-of-the-art fabrication and measurement tachniques for superconducting quantum circuits.
• Investigation of the fundamental light-matter interaction "on a chip" using superconducting quantum circuits.
• Quantum information theoretical concepts: Entanglement, quantum gates, quantum algorithms, quantum memories, quantum measurements etc.
• The coupling of nanomechanical systems and spin ensembles to superconducting circuits.
• Challenges: longer quantum coherence, higher gate fidelities, scalability to a large number of qubits etc.
• Latest developments on the strive towards quantum advantages over conventional technology
• Propagating quantum microwaves emitted by superconducting circuits: quantum ressources, quantum microwave communication, quantum radar

You will be supported in the preparation of your talks from the research groups on superconducting quantum circuits, propagating quantum microwaves, and nanomechanics at the Walther-Meißner-Institute.

Learning Outcome:

After the successful completion of the module the students are able

• To prepare presentation slides on a scientific topic and to clearly present a topical research field within a scientific talk.
• To discuss on a state-of-the-art research field in a scientific way.
• To analyze and assess the latest development in quantum scinece and technology with superconducting circuits.
• To understand and explain the foundations of superconducting quantum systems and technology.
• To understand the foundations and the state of the art in quantum computing, quantum simulation, quantum communication, quantum sensing, and quantum metrology with supercondcuting circuits
• To understand the foundations and the state of the art in nanomechnical systems and spin ensembles

Preconditions:

Basic knowledge of condensed matter physics, foundations of quantum mechanics