A cutting-edge ultra-coherent superconducting electro-mechanical system has been visualized using a scanning electron microscope. The image credit goes to Amir Youssefi of EPFL.
The team of scientists at EPFL have brought forth a superconducting circuit optomechanical platform that stands out for its extraordinary low quantum decoherence and high-precision quantum control. By employing what’s called a “vacuum-gap drumhead capacitor,” they’ve established the most extended quantum state lifetime ever recorded in a mechanical oscillator. This incredible advancement lays a promising foundation for future explorations in quantum computing and sensing.
The past ten years have seen remarkable strides in creating quantum phenomena within mechanical systems. What was once considered unattainable a mere fifteen years ago has been made possible by scientists who’ve managed to generate quantum states in large-scale mechanical objects.
Utilizing the connection between mechanical oscillators and light photons, known as “optomechanical systems,” researchers have achieved cooling these oscillators to a level near the quantum boundary. They have further managed to reduce their vibrations and even intertwine them. These breakthroughs have broadened the horizon for quantum sensing, miniature storage in quantum computing, foundational examinations of quantum gravity, and even probing for dark matter.
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The Challenge in Handling Optomechanical Systems
Optomechanical systems in the quantum realm present a unique challenge. The mechanical oscillators must be appropriately insulated from their surroundings to limit energy dissipation, yet adequately connected to other entities like electromagnetic resonators for effective control.
Achieving this equilibrium requires extending the oscillators’ quantum state lifetime, something that is negatively influenced by environmental thermal fluctuations and frequency instability in the oscillators—collectively referred to as “decoherence.” This problem spans across multiple systems, from enormous mirrors in gravitational wave detectors to minute particles in high vacuum, with opto- and electro-mechanical systems still experiencing higher decoherence rates than some other technologies.
EPFL’s Breakthrough: Exceptional Reduction in Quantum Decoherence
The team at EPFL, led by Tobias J. Kippenberg, has met this challenge head-on by constructing a superconducting circuit optomechanical platform that exhibits remarkably low quantum decoherence, while achieving substantial optomechanical coupling, enabling precise quantum control. The groundbreaking research was unveiled on August 10 in Nature Physics.
Amir Youssefi, the PhD student who spearheaded the project, expressed the significance by saying, “In layman’s terms, we’ve reached the most extended quantum state lifetime in a mechanical oscillator, something that can be utilized as a quantum storage component in quantum computing and communication systems. This is a major milestone that affects multiple fields, including quantum physics, electrical, and mechanical engineering.”
The Essential Component: Vacuum-Gap Drumhead Capacitor
Central to this advancement is the “vacuum-gap drumhead capacitor,” a vibratory piece composed of thin aluminum film poised over a silicon trench. It acts as the oscillating component and creates a resonant microwave circuit.
The team’s inventive nanofabrication technique notably cut down mechanical losses in the resonator, reaching an unparalleled thermal decoherence rate of only 20 Hz, equivalent to a quantum state lifetime of 7.7 milliseconds—the best ever in a mechanical oscillator.
Conclusions and Future Prospects
The drastic reduction in thermal decoherence enabled the researchers to apply an optomechanical cooling method, attaining an impressive 93% fidelity of the quantum state in the ground state. Moreover, they managed to squeeze the mechanical vibrations beneath the zero-point-fluctuation of motion to a value of -2.7 dB.
Shingo Kono, a research contributor, highlights, “This degree of control lets us observe mechanical squeezed states’ free evolution, maintaining its quantum nature for 2 milliseconds due to the extraordinarily low pure dephasing rate of only 0.09 Hz.”
Mahdi Chegnizadeh, another team member, adds, “Such incredibly low quantum decoherence improves the precision of quantum control and measurement in macroscopic mechanical systems, benefiting interfacing with superconducting qubits. It also positions the system for quantum gravity testing. The significantly longer storage time compared to superconducting qubits makes this platform ideal for quantum-storage applications.”
Reference: “A squeezed mechanical oscillator with millisecond quantum decoherence” by Amir Youssefi, Shingo Kono, Mahdi Chegnizadeh, and Tobias J. Kippenberg, published on August 10, 2023, in Nature Physics.
DOI: 10.1038/s41567-023-02135-y
The Center of MicroNanoTechnology (CMi) at EPFL was responsible for the fabrication of the device.
Frequently Asked Questions (FAQs) about Quantum Optomechanics
What is the key achievement of EPFL scientists in this research?
EPFL scientists have developed a superconducting circuit optomechanical platform with ultra-low quantum decoherence, achieving the longest quantum state lifetime in a mechanical oscillator, which holds promise for quantum computing and sensing applications.
What are optomechanical systems in the context of this research?
Optomechanical systems involve coupling mechanical oscillators to light photons. This interaction allows researchers to cool the oscillators to their lowest energy levels, reduce vibrations, and even entangle them, leading to new possibilities in quantum technology.
How does the “vacuum-gap drumhead capacitor” contribute to the breakthrough?
The “vacuum-gap drumhead capacitor” is a crucial element in this research. It is a vibrating component made of thin aluminum film suspended over a silicon trench. It serves as the basis for the oscillator and plays a pivotal role in achieving the remarkable reduction in mechanical losses and thermal decoherence.
What significance does the ultra-low quantum decoherence hold for quantum technologies?
The achievement of ultra-low quantum decoherence in the superconducting optomechanical platform has several implications. It enhances the precision of quantum control and measurements in mechanical systems, making it suitable for various applications, including interfacing with superconducting qubits, quantum gravity testing, and quantum-storage applications.
How does this research impact the fields of quantum physics and engineering?
This breakthrough impacts a wide range of audiences, including quantum physicists, electrical engineers, and mechanical engineers. It opens up new avenues for research and development in quantum computing, quantum communication, quantum sensing, and other related fields by providing a highly coherent platform for manipulating mechanical quantum states.
Where was the research conducted and published?
The research was conducted at the laboratory of Tobias J. Kippenberg at the École Polytechnique Fédérale de Lausanne (EPFL). The groundbreaking work was published in the journal Nature Physics on August 10, 2023.
What are the prospects for the future of this research?
The achieved ultra-low quantum decoherence and prolonged quantum state lifetime hold promise for practical applications in quantum technologies. This research could lead to advancements in quantum computing, precision measurements, and quantum information processing, further pushing the boundaries of our understanding of quantum phenomena.
More about Quantum Optomechanics
- EPFL News: Superconducting Optomechanical Breakthrough
- Nature Physics Article: “A squeezed mechanical oscillator with millisecond quantum decoherence”
