1985 paper on macroscopic quantum mechanics

Extracted Attributes

• Page

  1908

• Field

  Quantum Physics, Superconductivity

• Volume

  55

• Journal

  Physical Review Letters

• Primary Title

  Measurements of Macroscopic Quantum Tunneling out of the Zero-Voltage State of a Current-Biased Josephson Junction

• Publication Date

  1985-10-28

• Research Institution

  UC Berkeley

• Experimental Components

  Superconductors, Josephson Junction, Electrical Circuit

• Key Phenomenon Observed

  Quantum Tunneling

• Key Concept Demonstrated

  Macroscopic Quantum Mechanics

Timeline

• John Clarke, Michel Devoret, and John Martinis conducted a series of experiments at the University of California, Berkeley, demonstrating macroscopic quantum tunneling. (Source: web_search_results)

  1984-1985

• Publication of the paper 'Measurements of Macroscopic Quantum Tunneling out of the Zero-Voltage State of a Current-Biased Josephson Junction' by Michel H. Devoret, John M. Martinis, and John Clarke in Physical Review Letters. (Source: web_search_results)

  1985-10-28

• The paper demonstrated for the first time that a macroscopic object—an electrical circuit built with Superconductors and a Josephson Junction—exhibits quantum phenomena like Quantum Tunneling, proving Macroscopic Quantum Mechanics. (Source: summary, related_documents)

  1985

• John Martinis's team at Google achieved Quantum Supremacy, building upon the foundational work established by the 1985 paper. (Source: related_documents)

  2019

• John Martinis, John Clarke, and Michel Devoret are recognized as Nobel Prize in Physics winners for their work on macroscopic quantum mechanical tunneling, including the research detailed in this paper. (Source: related_documents, web_search_results)

  2025

Introduction to quantum mechanics

Quantum mechanics is the study of matter and matter's interactions with energy on the scale of atomic and subatomic particles. By contrast, classical physics explains matter and energy only on a scale familiar to human experience, including the behavior of astronomical bodies such as the Moon. Classical physics is still used in much of modern science and technology. However, towards the end of the 19th century, scientists discovered phenomena in both the large (macro) and the small (micro) worlds that classical physics could not explain. The desire to resolve inconsistencies between observed phenomena and classical theory led to a revolution in physics, a shift in the original scientific paradigm: the development of quantum mechanics. Many aspects of quantum mechanics yield unexpected results, defying expectations and deemed counterintuitive. These aspects can seem paradoxical as they map behaviors quite differently from those seen at larger scales. In the words of quantum physicist Richard Feynman, quantum mechanics deals with "nature as She is—absurd". Features of quantum mechanics often defy simple explanations in everyday language. One example of this is the uncertainty principle: precise measurements of position cannot be combined with precise measurements of velocity. Another example is entanglement: a measurement made on one particle (such as an electron that is measured to have spin 'up') will correlate with a measurement on a second particle (an electron will be found to have spin 'down') if the two particles have a shared history. This will apply even if it is impossible for the result of the first measurement to have been transmitted to the second particle before the second measurement takes place. Quantum mechanics helps people understand chemistry, because it explains how atoms interact with each other and form molecules. Many remarkable phenomena can be explained using quantum mechanics, like superfluidity. For example, if liquid helium cooled to a temperature near absolute zero is placed in a container, it spontaneously flows up and over the rim of its container; this is an effect which cannot be explained by classical physics.

Web Search Results

• Quantum Mechanics of a Macroscopic Variable - Science

  SCHWARTZ, D.B., QUANTITATIVE STUDY OF THE EFFECT OF THE ENVIRONMENT ON MACROSCOPIC QUANTUM TUNNELING, PHYSICAL REVIEW LETTERS 55: 1547 (1985). Web of Science Google Scholar VOSS, R.F., MACROSCOPIC QUANTUM TUNNELING IN 1-MU-M NB JOSEPHSON-JUNCTIONS, PHYSICAL REVIEW LETTERS 47: 265 (1981). Web of Science Google Scholar WASHBURN, S, EFFECTS OF DISSIPATION AND TEMPERATURE ON MACROSCOPIC QUANTUM TUNNELING, PHYSICAL REVIEW LETTERS 54: 2712 (1985). Web of Science Google Scholar [...] Google Scholar Schiff, L., Quantum Mechanics (1968). Google Scholar SCHWARTZ, D.B., QUANTITATIVE STUDY OF THE EFFECT OF THE ENVIRONMENT ON MACROSCOPIC QUANTUM TUNNELING, PHYSICAL REVIEW LETTERS 55: 1547 (1985). Web of Science Google Scholar VOSS, R.F., MACROSCOPIC QUANTUM TUNNELING IN 1-MU-M NB JOSEPHSON-JUNCTIONS, PHYSICAL REVIEW LETTERS 47: 265 (1981). Web of Science Google Scholar [...] WASHBURN, S, EFFECTS OF DISSIPATION AND TEMPERATURE ON MACROSCOPIC QUANTUM TUNNELING, PHYSICAL REVIEW LETTERS 54: 2712 (1985). Web of Science Google Scholar ZAIKIN, A.D., LIFETIME OF MACROSCOPIC CURRENT STATES, JETP LETTERS-USSR 43: 670 (1986). Google Scholar ZWERGER, W, INFLUENCE-FUNCTIONAL THEORY OF METASTABILITY IN A DISSIPATIVE QUANTUM SYSTEM, PHYSICAL REVIEW A 31: 1745 (1985). Web of Science Google Scholar ### Submit a Response to This Article ## (0)eLetters

• Macroscopic quantum mechanical tunnelling wins Nobel prize in ...

  # Macroscopic quantum mechanical tunnelling wins Nobel prize in physics By Jamie Durrani2025-10-07T11:55:00+01:00 No comments Source: © Niklas Elmehed/Nobel Prize Outreach John Clarke, Michel Devoret and John Martinis conducted their Nobel prize-winning work in 1985 [...] While quantum effects based on individual particles had previously been studied, Clarke, Devoret and Martinis’ findings were unique in that they revealed a quantum effect that is macroscopic – based on many particles working in unison. [...] In particular, they sought to measure phenomena occurring across a Josephson junction – where two superconducting components are separated by a layer of non-conducting material. The team observed a tunnelling effect where a current was able to cross this gap. They then used microwaves to analyse how the system’s behaviour changed in response to specific amounts of energy.

• Nobel Prize: Quantum Tunneling on a Large Scale (Updated)

  #### Measurements of Macroscopic Quantum Tunneling out of the Zero-Voltage State of a Current-Biased Josephson Junction Michel H. Devoret, John M. Martinis, and John Clarke Phys. Rev. Lett. 55, 1908 (1985) Published October 28, 1985 ## Subject Areas Quantum PhysicsSuperconductivity ## Related Articles Quantum Physics ### Secure Quantum Communication Breaks Distance Record [...] 1. M. H. Devoret et al., “Resonant activation from the zero-voltage state of a current-biased Josephson Junction,” Phys. Rev. Lett. 53, 1260 (1984). 2. J. M. Martinis et al., “Energy-level quantization in the zero-voltage state of a current-biased Josephson Junction,” Phys. Rev. Lett. 55, 1543 (1985). 3. M. H. Devoret et al., “Measurements of macroscopic quantum tunneling out of the zero-voltage state of a current-biased Josephson Junction,” Phys. Rev. Lett. 55, 1908 (1985). [...] Clarke, Devoret, and Martinis (all working at UC Berkeley at the time) designed an experiment that overcame the noise problem. Their system was a centimeter-wide superconducting circuit containing a Josephson junction. The superconducting electrons in the circuit form a collective system, essentially a macroscopic object, described by a single quantum phase. Previously developed models showed that this multielectron object can exist in one of two states, corresponding to zero voltage and

• Nobel Prize in Physics 2025 - Popular information - NobelPrize.org

  This year’s Nobel Prize in Physics recognises experiments that demonstrated how quantum tunnelling can be observed on a macroscopic scale, involving many particles. In 1984 and 1985, John Clarke, Michel Devoret and John Martinis conducted a series of experiments at the University of California, Berkeley. They built an electrical circuit with two superconductors, components that can conduct a current without any electrical resistance. They separated these with a thin layer of material that did [...] By the mid-1980s, Michel Devoret had joined John Clarke’s research group as a postdoc, after receiving his doctorate in Paris. This group also included the doctoral student John Martinis. Together, they took on the challenge of demonstrating macroscopic quantum tunnelling. Vast amounts of care and precision were necessary to screen the experimental setup from all the interference that could affect it. They succeeded in refining and measuring all the properties of their electrical circuit, [...] Figure 3. Initially, the experiment has no voltage at all. It is as if there is a lever in the off position, and something is blocking from being moved to on. Without the effects of quantum mechanics, this state would remain unchanged. Suddenly, a voltage appears. This is as if the lever has moved from off to on, despite the barrier between the two. What happened in the experiment is called macroscopic quantum tunnelling.©Johan Jarnestad/The Royal Swedish Academy of Sciences

• Quantum effects in electrical circuits honored with Physics Nobel

  The strange rules of quantum mechanics ordinarily hold sway only at subatomic scales. However, in 1985, three physicists coaxed distinctly quantum mechanical behavior out of a tiny circuit etched on a microchip—still tiny, but gigantic for the quantum realm. That feat paved the way for much of the current work on quantum computers. And today it earned the Nobel Prize in Physics for John Clarke of the University of California, Berkeley; Michel Devoret of Yale University; and John Martinis of UC [...] When cooled to near absolute zero, certain metals become superconductors, and a circuit built from them will carry a current with no resistance. Such flow arises when the electrons join in loosely associated pairs and those pairs condense into a single macroscopic wave. In Clarke’s lab, where Devoret was a postdoc and Martinis was a grad student, the trio demonstrated the existence of that macroscopic wave. They also proved it behaves quantum mechanically.