In this episode of The New Quantum Era, Sebastian talks with Martin Schultz, Professor at TU Munich and board member of the Leibniz Supercomputing Center (LRZ) about the critical need to integrate quantum computers with classical supercomputing resources to build practical quantum solutions. They discuss the Munich Quantum Valley initiative, focusing on the challenges and advancements in merging quantum and classical computing.

Main Topics Discussed:

• The Genesis of Munich Quantum Valley: The Munich Quantum Valley is a collaborative project funded by the Bavarian government to advance quantum research and development. The project quickly realized the need for software infrastructure to bridge the gap between quantum hardware and real-world applications.
• Building a Hybrid Quantum-Classical Computing Infrastructure: LRZ is developing a software stack and web portal to streamline the interaction between their HPC system and various quantum computers, including superconducting and ion trap systems. This approach enables researchers to leverage the strengths of both classical and quantum computing resources seamlessly.
• Hierarchical Scheduling for Efficient Resource Allocation: LRZ is designing a multi-tiered scheduling system to optimize resource allocation in the hybrid environment. This system considers factors like job requirements, resource availability, and the specific characteristics of different quantum computing technologies to ensure efficient execution of quantum workloads.
• Open-Source Collaboration and Standardization: LRZ aims to make its software stack open-source, recognizing the importance of collaboration and standardization in the quantum computing community. They are actively working with vendors to define standard interfaces for integrating quantum computers with HPC systems.
• Addressing the Unknown in Quantum Computing: The field of quantum computing is evolving rapidly, and LRZ acknowledges the need for adaptable solutions. Their architectural design prioritizes flexibility, allowing for future pivots and the incorporation of new quantum computing models and intermediate representations as they emerge.

Munich Quantum Valley
IEEE Quantum

Welcome to The New Quantum Era, a podcast hosted by Sebastian Hassinger and Kevin Rowney. In this episode, we have an insightful conversation with Dr. Toby Cubitt, a pioneer in quantum computing, a professor at UCL, and a co-founder of Phasecraft. Dr. Cubitt shares his deep understanding of the current state of quantum computing, the challenges it faces, and the promising future it holds. He also discusses the unique approach Phasecraft is taking to bridge the gap between theoretical algorithms and practical, commercially viable applications on near-term quantum hardware.

Key Highlights:

• The Dual Focus of Phasecraft: Dr. Cubitt explains how Phasecraft is dedicated to algorithms and applications, avoiding traditional consultancy to drive technology forward through deep partnerships and collaborative development.
• Realistic Perspective on Quantum Computing: Despite the hype cycles, Dr. Cubitt maintains a consistent, cautiously optimistic outlook on the progress toward quantum advantage, emphasizing the complexity and long-term nature of the field.
• Commercial Viability and Algorithm Development: The discussion covers Phasecraft’s strategic focus on material science and chemistry simulations as early applications of quantum computing, leveraging the unique strengths of quantum algorithms to tackle real-world problems.
• Innovative Algorithmic Approaches: Dr. Cubitt details Phasecraft’s advancements in quantum algorithms, including new methods for time dynamics simulation and hybrid quantum-classical algorithms like Quantum enhanced DFT, which combine classical and quantum computing strengths.
• Future Milestones: The conversation touches on the anticipated breakthroughs in the next few years, aiming for quantum advantage and the significant implications for both scientific research and commercial applications.

Papers Mentioned in this episode:

• Observing ground-state properties of the Fermi-Hubbard model using a scalable algorithm on a quantum computer
• Towards near-term quantum simulation of materials
• Enhancing density functional theory using the variational quantum eigensolver
• Dissipative ground state preparation and the Dissipative Quantum Eigensolver

Other sites:

• Phasecraft
• Dr. Toby Cubitt’s personal site

In this episode of The New Quantum Era podcast, hosts Sebastian Hassinger and Kevin Roney interview Jessica Pointing, a PhD student at Oxford studying quantum machine learning.

Classical Machine Learning Context

• Deep learning has made significant progress, as evidenced by the rapid adoption of ChatGPT
• Neural networks have a bias towards simple functions, which enables them to generalize well on unseen data despite being highly expressive
• This “simplicity bias” may explain the success of deep learning, defying the traditional bias-variance tradeoff

Quantum Neural Networks (QNNs)

• QNNs are inspired by classical neural networks but have some key differences
• The encoding method used to input classical data into a QNN significantly impacts its inductive bias
• Basic encoding methods like basis encoding result in a QNN with no useful bias, essentially making it a random learner
• Amplitude encoding can introduce a simplicity bias in QNNs, but at the cost of reduced expressivity
  • Amplitude encoding cannot express certain basic functions like XOR/parity
• There appears to be a tradeoff between having a good inductive bias and having high expressivity in current QNN frameworks

Implications and Future Directions

• Current QNN frameworks are unlikely to serve as general purpose learning algorithms that outperform classical neural networks
• Future research could explore:
  • Discovering new encoding methods that achieve both good inductive bias and high expressivity
  • Identifying specific high-value use cases and tailoring QNNs to those problems
  • Developing entirely new QNN architectures and strategies
• Evaluating quantum advantage claims requires scrutiny, as current empirical results often rely on comparisons to weak classical baselines or very small-scale experiments

In summary, this insightful interview with Jessica Pointing highlights the current challenges and open questions in quantum machine learning, providing a framework for critically evaluating progress in the field. While the path to quantum advantage in machine learning remains uncertain, ongoing research continues to expand our understanding of the possibilities and limitations of QNNs.

Paper cited in the episode:
Do Quantum Neural Networks have Simplicity Bias?

Sebastian is joined by Susanne Yelin, Professor of Physics in Residence at Harvard University and the University of Connecticut.
Susanne's Background:

• Fellow at the American Physical Society and Optica (formerly the American Optics Society)
• Background in theoretical AMO (Atomic, Molecular, and Optical) physics and quantum optics
• Transition to quantum machine learning and quantum computing applications

Quantum Machine Learning Challenges

• Limited to simulating small systems (6-10 qubits) due to lack of working quantum computers
• Barren plateau problem: the more quantum and entangled the system, the worse the problem
• Moved towards analog systems and away from universal quantum computers

Quantum Reservoir Computing

• Subclass of recurrent neural networks where connections between nodes are fixed
• Learning occurs through a filter function on the outputs
• Suitable for analog quantum systems like ensembles of atoms with interactions
• Advantages: redundancy in learning, quantum effects (interference, non-commuting bases, true randomness)
• Potential for fault tolerance and automatic error correction

Quantum Chemistry Application

• Goal: leverage classical chemistry knowledge and identify problems hard for classical computers
• Collaboration with quantum chemists Anna Krylov (USC) and Martin Head-Gordon (UC Berkeley)
• Focused on effective input-output between classical and quantum computers
• Simulating a biochemical catalyst molecule with high spin correlation using a combination of analog time evolution and logical gates
• Demonstrating higher fidelity simulation at low energy scales compared to classical methods

Future Directions

• Exploring fault-tolerant and robust approaches as an alternative to full error correction
• Optimizing pulses tailored for specific quantum chemistry calculations
• Investigating dynamics of chemical reactions
• Calculating potential energy surfaces for molecules
• Implementing multi-qubit analog ideas on the Rydberg atom array machine at Harvard
• Dr. Yelin's work combines the strengths of analog quantum systems and avoids some limitations of purely digital approaches, aiming to advance quantum chemistry simulations beyond current classical capabilities.