In this episode of The New Quantum Era, your host, Sebastian Hassinger sits down with Dr. Yvonne Gao, a leading experimental physicist specializing in superconducting devices and quantum cavities. Recorded at the American Physical Society's Global Summit, the conversation explores the intersection of curiosity-driven research and technological advancement in quantum physics.

Key Topics Discussed

1. Research Focus: Quantum Cavities and Superposition

• Dr. Gao shares her team's work on using cavities (harmonic oscillators) coupled with a single qubit to probe fundamental quantum effects.
• The experiments focus on quantum superposition and entanglement using minimal hardware—just one qubit and one cavity—eschewing the race for more qubits in favor of deeper scientific insights.
• Discussion of "cat states" as iconic demonstrations of quantum superposition, and how their properties can be engineered for robustness and sensitivity without specialized hardware.

2. Experimental Innovation

• The team investigates loss mechanisms in cavity-based quantum states and explores ways to make these states more resilient through state engineering rather than hardware changes.
• Dr. Gao describes using standard, "vanilla" qubits and cavities, making their techniques accessible to other labs.

3. Fundamental Questions and Quantum Playground

• Dr. Gao emphasizes the value of the circuit QED platform as a "playground" for exploring quantum phenomena, particularly entanglement and its quantification in real hardware.
• The challenge of visualizing and intuitively understanding quantum phenomena is highlighted, with experiments designed to make abstract concepts more tangible.

4. Device Fabrication and Advancements

• Dr. Gao's lab at NUS has developed in-house fabrication capabilities, gradually building up expertise and infrastructure.
• The field is witnessing rapid improvements in device performance, driven by advances in materials science and process integration.

5. Multipartite Entanglement and Future Directions

• Plans for multi-cavity devices: Moving from single and two-cavity systems to three, enabling the study of tripartite entanglement and richer quantum dynamics.
• The potential for these systems to serve as both research tools and pedagogical aids, demonstrating quantum strangeness in a hands-on way.

6. Synergy Between Science and Technology

• The conversation explores the unique moment in quantum research where fundamental science and technological objectives are closely aligned.
• Knowledge flows both ways: curiosity-driven experiments inform processor design, while industrial advances in fabrication and control benefit academic labs.

7. The "Perfect Quantum Lab" Thought Experiment

• Dr. Gao shares her wish list for a hypothetical, fault-tolerant quantum computer: to directly observe textbook quantum phenomena and simulate complex quantum behaviors in a tangible way.

Memorable Quotes

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In this episode, your host Sebastian Hassinger sits down with Andrew Houck to explore the latest advancements and collaborative strategies in quantum computing. Houck shares insights from his leadership roles at both Princeton and the Center for Co-Design of Quantum Advantage (C2QA), focusing on how interdisciplinary efforts are pushing the boundaries of coherence times, materials science, and scalable quantum architectures. The conversation covers the importance of co-design across the quantum stack, the challenges and surprises in improving qubit performance, and the vision for the next era of quantum research.

KEY TOPICS DISCUSSED

• Mission of C2QA:
  The central goal is to build the components necessary to move beyond the NISQ (Noisy Intermediate-Scale Quantum) era into fault-tolerant quantum computing. This requires integrating expertise in materials, devices, software, error correction, and architecture to ensure compatibility and progress at every level.
• Materials Breakthroughs:
  Houck discusses the surprising impact of using tantalum in superconducting qubits, which has significantly reduced surface losses compared to other metals. He explains the ongoing quest to identify and mitigate sources of decoherence, such as two-level systems (TLSs) and interface defects.
• Co-Design Philosophy:
  The episode delves into two types of co-design:
  • Vertical co-design: Aligning advances in materials, devices, error correction, and architecture to optimize the full quantum computing stack.
  • Cross-platform co-design: Bridging ideas and techniques across different qubit modalities and even across disciplines, such as applying methods from quantum sensing to quantum computing.
• Error Correction Innovations:
  Houck highlights breakthroughs like using GKP states for error correction, which have achieved performance beyond the break-even point, thanks to improvements in materials and device design.
• Bosonic Modes and Custom Architectures:
  The conversation touches on leveraging native bosonic modes in hardware to simulate field theories more efficiently, potentially saving vast computational resources. Houck discusses the trade-offs between general-purpose and custom quantum circuits in the current era of limited qubit counts.
• Modular Quantum Computing:
  As quantum systems scale, the focus is shifting to modular architectures. Houck outlines the challenges of connecting modules—such as chip-to-chip coupling and optimizing connectivity for error correction and algorithms.
• Institutional Collaboration:
  Houck contrasts the long-term, foundational investment at Princeton with the national, multi-institutional mission of C2QA. He emphasizes the unique strengths universities, industry, and national labs each bring to quantum research, and the importance of fostering collaboration across these sectors.
• Looking Ahead:
  The next phase for C2QA will incorporate advances in neutral atom quantum computing and diamond-based quantum sensing, while ramping down some networking efforts. Houck also reflects on the broader scientific and practical motivations driving quantum information science, and the fundamental questions that large-scale quantum systems may help answer.

NOTABLE QUOTES

“There’s a quasi-infinite number of ways that you can mess up coherence… If you’re really only using one number, you’ll never know.”

“Some of the best ideas we have are taking approaches from one field and bringing them to another. That’s what we call cross-platform co-design.”

“A million-qubit quantum computer is basically a cat… as you build these systems up, you can start to really ask: do we actually understand quantum mechanics as it turns into these macroscopically large objects?”

RESOURCES & MENTIONS

• Center for Co-Design of Quantum Advantage (C2QA)
• Princeton Quantum Initiative

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In this episode of The New Quantum Era, Sebastian is joined by Dr. Emily Edwards, a co-founder of the Q12 initiative, an NSF-funded effort aimed at enhancing quantum science education from middle school through early undergraduate levels. Emily brings her expertise in organizing and motivating educators, as well as her passion for science communication. In this episode, we delve into the unique challenges of teaching quantum science and explore effective strategies to make this abstract field more accessible to learners of all ages.

Key Points

• Challenges in Quantum Communication and Education: Emily discusses the public perception of quantum science, often influenced by pop culture, and the importance of demystifying the subject to make it more approachable.
• Strategies for Formal and Informal Learning: The conversation highlights different techniques for teaching quantum science in formal settings, like schools, and informal settings, such as science museums or YouTube. Emily emphasizes the importance of foundational knowledge and incremental learning.
• Role of Technology in Quantum Education: Emily talks about using scanning electron microscopes and other technologies to make the invisible world of quantum science visible, thus igniting public interest and imagination similar to stargazing.
• Importance of Science Communication Workshops: Emily shares her experience in leading science communication workshops, aiming to improve the accuracy and effectiveness of science content created by the public.
• Public and Private Sector Collaboration: The discussion touches on the need for a blend of federal and private funding to sustain and scale quantum education initiatives. Emily stresses the importance of industry involvement to emphasize the urgency and importance of scientific literacy for the future workforce.