Phonon-Number-Sensitive Electromechanics

Area of Science:

• Quantum Electromechanics
• Superconducting Circuits
• Nanoscale Oscillators

Background:

• Micromechanical oscillators are crucial for sensing applications.
• Superconducting qubits offer precise quantum control.
• Integrating these systems presents challenges in coupling and detection.

Purpose of the Study:

• To directly detect and control the energy of a micromechanical oscillator using a superconducting qubit.
• To explore quantum nondemolition measurements and nonclassical state preparation.
• To investigate the nonlinear interaction between a qubit and an oscillator.

Main Methods:

• Utilizing the intrinsic nonlinearity of a microwave superconducting qubit (4 GHz).
• Electrostatic coupling between the qubit and a 25 MHz micromechanical oscillator.
• Analyzing qubit frequency shifts to determine oscillator phonon number distribution.

Main Results:

• Qubit frequency shifts by 0.52 MHz per oscillator phonon.
• Extracted phonon number distribution from qubit lineshape.
• Created nonthermal states by manipulating oscillator energy levels.
• Cooled the oscillator, increasing ground state population by a factor of 8.

Conclusions:

• Demonstrated a novel electromechanical system for quantum control.
• The qubit acts as a sensitive vibrational energy detector.
• This approach is promising for quantum nondemolition measurements and nonclassical state generation.