Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Multi-cavity ultra-stable laser towards 10-18   In this letter, we demonstrate a technique of making an ultrastable laser
referenced to a multi-cavity, corresponding to a lower thermal noise limit due
to the larger equivalent beam size. The multi-cavity consists of several pairs
of mirrors and a common spacer. We can stabilize the laser frequencies on these
cavities, and average the laser frequencies with synthesizing technique. In
comparison with a single cavity system, relative frequency instability of the
synthesized laser can be improved by a factor of the squire root of the cavity
number (n). In addition, we perform an experiment to simulate a two-cavity
system. Experimental results show that frequency instability of the synthesized
laser is improved by a factor of 1.4, and discrimination of the laser frequency
instability, introduced by the process of lasers synthesizing, is negligible,
and can reach a floor at low level 10-18 limited by noise of currently used
signal generators. This technique is comparable with other techniques; thus, it
can gain a factor of the squre root of n on the frequency instability of an
ultrastable laser to an unprecedented level.

23
The categories of this paper are: solv-int
34
The categories of this paper are: chem-ph
24
The categories of this paper are: dg-ga
19
The categories of this paper are: eess
16
The categories of this paper are: stat
29
The categories of this paper are: funct-an
36
The categories of this paper are: cmp-lg
6
The categories of this paper are: astro-ph
37
The categories of this paper are: supr-con
4
The categories of this paper are: cond-mat
30
The categories of this paper are: q-alg
7
The categories of this paper are: hep-th
20
The categories of this paper are: acc-phys
1
The categories of this paper are: cs
28
The categories of this paper are: alg-geom
31
The categories of this paper are: ao-sci