Shot‐Noise‐Driven Macroscopic Vibrations and Displacement Transduction in Quantum Tunnel Junctions

Journal Article · Sat Jul 12 00:00:00 EDT 2025 · Annalen der Physik (Leipzig)

DOI:https://doi.org/10.1002/andp.202500030· OSTI ID:2583714

Kumbhakar, Prasanta ^[1]; Shanmugam, Anusha ^[1]; Mishra, Akhileshwar ^[1]; Pant, Ravi ^[1]; Reno, John L. ^[2]; Addamane, Sadhvikas ^[2]; Thalakulam, Madhu ^[1]

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1. Indian Institute of Science Education and Research (IISER), Thiruvananthapuram (India)
2. Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States). Center for Integrated Nanotechnologies

Back‐action is an inevitable result of quantum measurement. Although the microscopic impacts of shot‐noise back‐action have been explored, macroscopic evidence is seldom documented, especially in the field of electrical transport. Tunneling shot‐noise has been shown to excite the fundamental flexural mode of the host crystal using a sub‐GHz lumped‐element radio‐frequency quantum point contact (QPC). Here, in this study, this aspect of shot‐noise back‐action is examined at much higher operational frequencies and wider bandwidths by employing a GaAs QPC integrated into a planar superconducting cavity within the circuit‐QED framework, leading to the observation of the excitation of multiple mechanical modes. The device operates in the shot‐noise‐limited regime. Constructed on a piezoelectric platform, there is positive feedback between the electrical and mechanical degrees of freedom within the QPC. Shot‐noise excites piezoelectric vibrational modes; concurrently the resulting polarization charges enhance tunneling and develop peaks in the shot‐noise spectra at the modal frequencies. The excitation of vibrational modes is a macroscopic demonstration of measurement back‐action, and the amplitudes of the noise‐peaks enable us to calibrate the displacement sensitivity of the QPC‐resonator systems, which is in the range $≈ 35 fm/√ Hz$, making it an excellent sensor for ultra‐sensitive and rapid strain/displacement detection.

• Research Organization: Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities (SUF)
• Grant/Contract Number: NA0003525
• OSTI ID: 2583714
• Journal Information: Annalen der Physik (Leipzig), Journal Name: Annalen der Physik (Leipzig) Journal Issue: 10 Vol. 537; ISSN 0003-3804; ISSN 1521-3889
• Publisher: Wiley
• Country of Publication: United States
• Language: English