Star Talk Nobel Prize Edition 2025: Macroscopic Quantum Tunneling and Quantum Computing Explained

Overview

In this Nobel Prize edition of Star Talk, Neil deGrasse Tyson chats with John Martinis about how quantum mechanics can allow a system to behave as both 0 and 1, the concept of macroscopic quantum tunneling in electric circuits, and the implications for quantum computing and encryption.

Key takeaways

Martinis explains how superconducting circuits host qubits, how tens of qubits create enormous parallel computational states, and why the Nobel Prize recognized foundational work that bridges fundamental physics and practical devices. The conversation also covers cryptography, quantum supremacy versus quantum advantage, and the challenges of building reliable quantum hardware.

Introduction and context

The Nobel Prize edition of Star Talk features host Neil deGrasse Tyson, with guests Professor John Martinis and Chuck Knight, discussing the dramatic convergence of fundamental quantum physics and practical quantum technologies. The conversation centers on macroscopic quantum phenomena in engineered devices, how these ideas underpin quantum computing, and what the Nobel Prize recognizes in this field. The tone blends rigorous physics explanations with accessible analogies and lighthearted banter, illustrating how ideas once confined to abstract theory have become the foundation of a new computing paradigm.

Quantum mechanics in the everyday world

Martinis explains that quantum laws can apply to systems large enough to be seen with the naked eye when many constituents act coherently. He notes that superconducting circuits can exhibit quantum behavior, with currents and voltages obeying quantum rules. A key point is that macroscopic quantum phenomena are not simply “at atomic scales” but can emerge in engineered systems that are millimeters in size, thereby bridging microscopic theory and macroscopic observation. The discussion uses crystal analogies to illustrate how repeating microscopic quantum rules can manifest as macroscopic order, while also emphasizing that the underlying physics remains quantum in nature.

Qubits and quantum computation

The panel provides a primer on qubits, comparing them to classical bits while highlighting the essential difference: a qubit can be in a superposition of 0 and 1. They explain parallelism: with n qubits, the number of possible states scales exponentially, enabling computations in parallel that would be infeasible for a classical computer. The dialogue emphasizes that simply having a large number of states is not enough; algorithms must be designed to extract useful results from this parallelism. They quantify the growth: 2^3 states for three qubits, 2^53 states for fifty-three qubits, and astronomically large state spaces for larger systems, which underscores both the potential power and the engineering challenges involved.

From theory to hardware

The conversation delves into the hardware advances that make quantum computing possible, focusing on superconducting qubits and Josephson junctions. Martinis describes how the quantum phase and Cooper pairs enable coherent operations in circuits built from inductors, capacitors, and transmission lines. The team discusses the role of cryogenic cooling to minimize thermal noise and the issue of decoherence as a fundamental hurdle for maintaining quantum states long enough to perform computations. They contrast traditional electronics with quantum devices, describing a new kind of periodic table built from quantum elements rather than atoms, and how this opens avenues for new devices with quantum behavior.

Historical arc and Nobel recognition

The discussion covers the historical evolution from early quantum experiments to practical qubit implementations. Martinis explains how the 1985 theoretical work laid groundwork for decades of experiments, culminating in a Nobel Prize recognizing macroscopic quantum phenomena in circuits and their application to quantum computing. The participants reflect on the delay between discovery and recognition, noting that scientific impact often becomes clear only over long timescales as research matures into technology with wide-ranging implications.

Quantum computation and cryptography

A central theme is the transformative potential of quantum computing for cryptography. The group discusses Shor’s algorithm, which can factor large numbers efficiently and threaten widely used cryptographic schemes such as RSA. They emphasize that cryptography has a built-in finite lifetime as quantum capabilities advance, and stress the need for quantum-safe cryptography. They also discuss how governments and institutions might manage this transition responsibly, drawing parallels with AI governance in terms of proactive regulation and coordinated standards development.

Quantum supremacy versus quantum advantage

The hosts differentiate quantum supremacy from quantum advantage, explaining that early demonstrations showed quantum computers solving tasks beyond classical capabilities, while ongoing work aims to achieve practical, widely beneficial applications. They acknowledge that achieving useful, robust quantum advantage requires not just more qubits but improved error correction and algorithm design, as well as scalable hardware with low error rates.

Hardware challenges and future directions

With qubit counts in the hundreds and thousands, the field is racing toward devices that maintain coherence long enough for meaningful computations. The conversation highlights different hardware approaches, including superconducting qubits and neutral-atom platforms, and notes that the best path forward may involve a combination of architectures and co-processors to complement classical computers. The piece also touches on the Willow chip and its evolution, signaling healthy, ongoing progress in hardware engineering and software tooling to unlock practical use cases.

AI, policy, and the broader science ecosystem

The discussion broadens to policy and governance, acknowledging that quantum technologies will raise questions about security, privacy, and societal impact. The speakers suggest leveraging governance models similar to those developed for AI, emphasizing transparency, security-by-design, and responsible research pathways. They also touch on the potential cross-pollination between quantum computing and AI research, particularly in solving quantum-mechanical problems and accelerating scientific discovery through improved modeling and simulation.

Applications and long-term outlook

Beyond cryptography, potential applications include materials discovery, optimization problems, quantum simulation of complex systems, and even weather prediction. The guests stress that early quantum devices will be used as co-processors to augment traditional computing resources, rather than replacing them outright. As hardware scales and algorithms mature, enterprises and researchers will explore more sophisticated problems, ultimately expanding the practical scope of quantum computing across science, engineering, and industry. The dialogue ends by reaffirming the excitement around quantum physics and its transformative potential, while acknowledging the practical hurdles that must be overcome in the coming decades.