  We propose a theoretical scheme to enhance the signal-to-noise ratio in
ultrasensitive detection with the help of quantum correlation. By introducing
the auxiliary oscillator and treated as an added probe for weak field
detection, the additional noise can be greatly suppressed and the measurement
accuracy may even break the standard quantum limit. We use the magnetic field
as an example to exhibit the detection capability of our scheme. The result
show that, comparing with the traditional detection protocol, our scheme can
have higher signal-to-noise ratio and better detection accuracy. Furthermore,
the signal intensity detection curve shows a good linearity. Our results
provide a promising platform for reducing the additional noise by utilizing
quantum correlation in ultrasensitive detection.
