September 17, 2025
The Second Quantum Revolution
Andrew Houck
Dean of the Princeton University School of Engineering and Applied Science and Anthony H.P. Lee '79 Professor of Electrical and Computer Engineering
He was the inaugural co-director of the Princeton Quantum Initiative.
The Second Quantum Revolution
Andrew Houck
Dean of the Princeton University School of Engineering and Applied Science and Anthony H.P. Lee '79 Professor of Electrical and Computer Engineering
He was the inaugural co-director of the Princeton Quantum Initiative.
Lynne Durkee, introducer, and Andrew Houck
Minutes of the Second Meeting of the 84th Year
George Bustin, Old Guard President, called the meeting to order and presided. Cynthia Woolston-Maltenfort led the invocation. The attendance at the Nassau Club was 134. There were two guests: Katherine Kish (guest of Ralph Widner) and Ben Duffy (guest of Steve Silverman). Sarah Ringer read the minutes of the September 10 meeting.
Lynne Durkee introduced the speaker, Professor Andrew Houck, the new Dean of Princeton University’s School of Engineering and Applied Science and a professor on the electrical and computer engineering faculty since 2008. He serves as co-director of the Princeton Quantum Initiative and director of one of the five US DOE-funded Quantum Computer Institutes, which is being built on the Princeton campus.
Houck narrated an excellent introduction to modern quantum physics, motivating the audience by describing the potential for quantum computing to solve “impossible” problems. He began with a simple two-slit classical physics thought experiment. If particles go through a pair of parallel slits, they will be detected in two rows, whereas if waves go through two slits, they will produce an interference or diffraction pattern. However, if individual particles or very small particles go through such slits, they always produce an interference pattern, via the principle of superposition. This quantum behavior has been known for a hundred years.
As Houck explained, our senses do not operate at the atomic level and thus we do not have any intrinsic “feel” for this observation of a Superposition pattern. In addition, at this scale, the act of measurement is an interference, the Heisenberg Uncertainty Principle. Two key early technical products that resulted from this first quantum revolution were (1) the transistor (first developed at Bell Labs in New Jersey in 1947-1948), and (2) the laser (which relies on atoms having discreet energy levels, developed originally in 1960 at Hughes Aircraft). These days transistors are being manufactured at a rate of a trillion per second.
However, from the 1980’s, three more advanced quantum principles are being utilized to create a second quantum revolution. The first is the principle of Superposition – think Schrodinger’s cat being both alive and dead at the same time. Its application in quantum computing is simultaneously accessing superposition states (provided the material is cold enough, degrees milli-Kelvin). The second is the principle of Quantum Entanglement, Einstein’s spooky interaction at great distances. This allows for nanoscale (millionth of a millimeter) probes, useful for biological applications, and magnetic field probes for enhanced GPS. The third is the Principle of Measurement Disturbance, stated as the Heisenberg Uncertainty Principle. When applied to communication, this permits the detection of eavesdropping.
Then Houck described a simple example using three “bits” to illustrate the advantage of a quantum computer to provide a more efficient and correct answer; even a difficult problem would take hours and not years. He presented a diagram of the challenge for quantum computer architecture: (a) to begin with circuits built from superconducting materials and make them faster, or (b) begin with individual atoms and make them more stable. Princeton’s approach is from the circuit side. He showed us a typical state-of-the-art dilution refrigerator, as shown in a recent Time magazine cover, standard technology to produce temperatures below one degree Kelvin.
The challenge to improving speed and output is removing “dirt,” as a generic term for impurities, temperature fluctuations and vibrations. The new Quantum Institute brings together multiple disciplines to provide ideas and solutions for all these challenges. Houck predicted that quantum computing should be usefully solving problems in about five years.
Respectfully submitted,
Julianne Elward-Berry
Lynne Durkee introduced the speaker, Professor Andrew Houck, the new Dean of Princeton University’s School of Engineering and Applied Science and a professor on the electrical and computer engineering faculty since 2008. He serves as co-director of the Princeton Quantum Initiative and director of one of the five US DOE-funded Quantum Computer Institutes, which is being built on the Princeton campus.
Houck narrated an excellent introduction to modern quantum physics, motivating the audience by describing the potential for quantum computing to solve “impossible” problems. He began with a simple two-slit classical physics thought experiment. If particles go through a pair of parallel slits, they will be detected in two rows, whereas if waves go through two slits, they will produce an interference or diffraction pattern. However, if individual particles or very small particles go through such slits, they always produce an interference pattern, via the principle of superposition. This quantum behavior has been known for a hundred years.
As Houck explained, our senses do not operate at the atomic level and thus we do not have any intrinsic “feel” for this observation of a Superposition pattern. In addition, at this scale, the act of measurement is an interference, the Heisenberg Uncertainty Principle. Two key early technical products that resulted from this first quantum revolution were (1) the transistor (first developed at Bell Labs in New Jersey in 1947-1948), and (2) the laser (which relies on atoms having discreet energy levels, developed originally in 1960 at Hughes Aircraft). These days transistors are being manufactured at a rate of a trillion per second.
However, from the 1980’s, three more advanced quantum principles are being utilized to create a second quantum revolution. The first is the principle of Superposition – think Schrodinger’s cat being both alive and dead at the same time. Its application in quantum computing is simultaneously accessing superposition states (provided the material is cold enough, degrees milli-Kelvin). The second is the principle of Quantum Entanglement, Einstein’s spooky interaction at great distances. This allows for nanoscale (millionth of a millimeter) probes, useful for biological applications, and magnetic field probes for enhanced GPS. The third is the Principle of Measurement Disturbance, stated as the Heisenberg Uncertainty Principle. When applied to communication, this permits the detection of eavesdropping.
Then Houck described a simple example using three “bits” to illustrate the advantage of a quantum computer to provide a more efficient and correct answer; even a difficult problem would take hours and not years. He presented a diagram of the challenge for quantum computer architecture: (a) to begin with circuits built from superconducting materials and make them faster, or (b) begin with individual atoms and make them more stable. Princeton’s approach is from the circuit side. He showed us a typical state-of-the-art dilution refrigerator, as shown in a recent Time magazine cover, standard technology to produce temperatures below one degree Kelvin.
The challenge to improving speed and output is removing “dirt,” as a generic term for impurities, temperature fluctuations and vibrations. The new Quantum Institute brings together multiple disciplines to provide ideas and solutions for all these challenges. Houck predicted that quantum computing should be usefully solving problems in about five years.
Respectfully submitted,
Julianne Elward-Berry