Related Experiment Video
Updated: Mar 13, 2026
11:03
An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids
Published on: December 4, 2017
9.1K
Quantum Backaction Evading Measurement of Collective Mechanical Modes
C F Ockeloen-Korppi1, E Damskägg1, J-M Pirkkalainen1
1Department of Applied Physics, Aalto University, P.O. Box 15100, FI-00076 AALTO, Finland.
Physical Review Letters
|October 15, 2016
Summary
Researchers demonstrated quantum backaction evading measurements for two mechanical oscillators. This technique overcomes the standard quantum limit for precise oscillator measurements, enabling advanced quantum sensing and entanglement.
Area of Science:
- Quantum mechanics
- Optomechanics
- Quantum sensing
Background:
- The standard quantum limit (SQL) fundamentally restricts the precision of oscillator position measurements due to the interplay of imprecision and quantum backaction.
- Measuring only a single quadrature of an oscillator allows for the evasion of quantum backaction, potentially enabling measurements of arbitrary precision.
Purpose of the Study:
- To demonstrate quantum backaction evading measurements for a collective quadrature of two coupled mechanical oscillators.
- To explore the potential for quantum state tomography of multiple mechanical oscillators.
- To lay the groundwork for macroscopic mechanical entanglement and advanced force sensing beyond the SQL.
Main Methods:
- Utilized two mechanical oscillators coupled to a common microwave cavity.
- Implemented quantum backaction evading measurement techniques on a collective quadrature of the oscillators.
- Performed quantum state tomography on the mechanical oscillators.
Main Results:
- Successfully demonstrated quantum backaction evading measurements on a collective quadrature of two coupled mechanical oscillators.
- Achieved measurements that surpass the standard quantum limit.
- Enabled quantum state tomography for the two-oscillator system.
Conclusions:
- Quantum backaction evading measurements can be effectively implemented in multi-oscillator systems.
- This technique provides a pathway towards macroscopic mechanical entanglement.
- The demonstrated method advances the capabilities of quantum-limited force sensing.
Related Concept Videos
02:45The Quantum-Mechanical Model of an Atom
60.9K
Shortly after de Broglie published his ideas that the electron in a hydrogen atom could be better thought of as being a circular standing wave instead of a particle moving in quantized circular orbits, Erwin Schrödinger extended de Broglie’s work by deriving what is now known as the Schrödinger equation. When Schrödinger applied his equation to hydrogen-like atoms, he was able to reproduce Bohr’s expression for the energy and, thus, the Rydberg formula governing hydrogen spectra.
60.9K
02:32The de Broglie Wavelength
34.2K
In the macroscopic world, objects that are large enough to be seen by the naked eye follow the rules of classical physics. A billiard ball moving on a table will behave like a particle; it will continue traveling in a straight line unless it collides with another ball, or it is acted on by some other force, such as friction. The ball has a well-defined position and velocity or well-defined momentum, p = mv, which is defined by mass m and velocity v at any given moment. This is the typical...
34.2K
01:17Magnetic Damping
1.2K
Eddy currents can produce significant drag on motion, called magnetic damping. For instance, when a metallic pendulum bob swings between the poles of a strong magnet, significant drag acts on the bob as it enters and leaves the field, quickly damping the motion.
If, however, the bob is a slotted metal plate, the magnet produces a much smaller effect. When a slotted metal plate enters the field, an emf is induced by the change in flux; however, it is less effective because the slots limit the...
If, however, the bob is a slotted metal plate, the magnet produces a much smaller effect. When a slotted metal plate enters the field, an emf is induced by the change in flux; however, it is less effective because the slots limit the...
1.2K
01:12Classical Mechanics
56
Classical mechanics provides a mathematical description of the motion of bodies under the influence of forces. A key principle within this field is the work-energy theorem, which establishes a bridge between the net work done on an object and its kinetic energy.The work-energy theorem states that the net work done on a particle by all the forces acting on it equals the change in its kinetic energy.In simple terms, the work-energy theorem is a method to analyze the effects of forces on an...
56
01:04Modes of Standing Waves: II
1.9K
The starting point for expressing the modes of standing waves is understanding the boundary conditions that the waves must follow. The boundary conditions are derived from the physical understanding of how the standing waves are sustained, that is, how the vibrating particles of the medium behave at the boundaries imposed on them.
For a tube open at one end and closed at the other filled with air, the modes are such that there is always an antinode at the open end and a node at the closed end....
For a tube open at one end and closed at the other filled with air, the modes are such that there is always an antinode at the open end and a node at the closed end....
1.9K
01:09Conservation of Angular Momentum
16.4K
A system's total angular momentum remains constant if the net external torque acting on the system is zero. Considering a system that consists of n tiny particles, the angular momentum of any tiny particle may change, but the system's total angular momentum would remain constant. The principle of conservation of angular momentum only considers the net external torque acting on the system. While there are internal forces exerted by different particles within the system that also produce...
16.4K