Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quantum back-action evading measurement of collective mechanical modes   The standard quantum limit constrains the precision of an oscillator position
measurement. It arises from a balance between the imprecision and the quantum
back-action of the measurement. However, a measurement of only a single
quadrature of the oscillator can evade the back-action and be made with
arbitrary precision. Here we demonstrate quantum back-action evading
measurements of a collective quadrature of two mechanical oscillators, both
coupled to a common microwave cavity. The work allows for quantum state
tomography of two mechanical oscillators, and provides a foundation for
macroscopic mechanical entanglement and force sensing beyond conventional
quantum limits.

7
The categories of this paper are: hep-th
9
The categories of this paper are: nlin
31
The categories of this paper are: ao-sci
29
The categories of this paper are: funct-an
24
The categories of this paper are: dg-ga
2
The categories of this paper are: math
14
The categories of this paper are: math-ph
19
The categories of this paper are: eess
12
The categories of this paper are: nucl-th
28
The categories of this paper are: alg-geom
15
The categories of this paper are: nucl-ex
11
The categories of this paper are: hep-lat
36
The categories of this paper are: cmp-lg
3
The categories of this paper are: physics
23
The categories of this paper are: solv-int
27
The categories of this paper are: comp-gas