The precision enhancement is demonstrated in an optical spatial measurement
based on weak value amplification (WVA) system and split-like detection, by
injecting a TEM10 squeezed vacuum beam. It is the first time combining the WVA
technique and squeezed beam injection to experimentally realize high-precision
optical spatial measurement beyond the standard quantum limit. As a result, the
precision enhancement of 1.3 times can be achieved at 500kHz by adding a
squeezed beam in the vacuum input port of the Mach-Zehnder interferometer. The
minimum measurable displacement is reduced from 1.08pm to 0.85pm and the
corresponding minimum measurable tilt is reduced from 0.86prad to 0.67prad.
Moreover, the spatial measurement at low-frequency band is also implemented and
the SNR is improved 2dB at 4kHz. Our work provides an effective method to
accomplish higher precision in optical spatial measurement, which has potential
applications in gravitational wave interferometer calibration, super-resolution
quantum imaging, etc.Comment: 4 pages, 5 figures