Seminário do LMCAL/IFUSP
The Speed Limit of Quantum Measurement (and what we can achieve if we break it...)
Prof. Avi Peer (Physics Department and BINA Center for Nanotechnology Bar Ilan University, Israel
Data: 19/10/2018, às 15h.
Local: Auditório Norte.
Abstract:
Homodyne measurement is a corner-stone of quantum optics. It measures the fundamental variables of quantum electrodynamics - the quadratures of light, which constitute the optical analog of position and momentum. Yet, standard homodyne, which is used to measure quadratures, suffers from a severe bandwidth limitation: While the bandwidth of optical states can easily span many THz, standard homodyne detection is inherently limited to the electrically accessible, MHz-to-GHz range, leaving a dramatic gap between the relevant optical phenomena and the measurement capability.
We recently demonstrated a fully parallel optical homodyne measurement across an arbitrary optical bandwidth, effectively lifting the bandwidth limitation completely 1. Using optical parametric amplification, which amplifies one quadrature while attenuating the other, we could measure quadrature squeezing simultaneously across a bandwidth of 55THz.
I will review the broad context of quantum measurement and will present our parametric homodyne method and results. I will then discuss two immediate applications of parametric homodyne: First, broadband Quantum Key Distribution, where many quantum channels of communication can be multiplexed over a single broadband squeezer and using a single homodyne device. Second, Squeezing-enhanced Raman spectroscopy, where the detection sensitivity can surpass the shot-noise limit with a nonlinear interferometry scheme.
Yaakov Shaked, Yoad Michael, Rafi Vered, Leon Bello, Michael Rosenbluh and Avi Peer, Lifting the Bandwidth limit of Optical Homodyne Measurement, Nature Comm. 9, 609 (2018).
