On the Possibility of Converting Phase and Frequency Modulation of Light into Amplitude Modulation

Xiubin Liu, Feng-Dong Jia, Huaiyu Zhang +8 more

Recently, a Rydberg atom-based mixer was developed to measure the phase of a radio frequency (RF) field. The phase of the signal RF (SIG RF) field is down-converted directly to the phase of a beat signal created by the presence of a local RF (LO RF) field. In this study, we propose that the Rydberg atom-based mixer can be converted to an all-optical phase detector by amplitude modulation (AM) of the LO RF field; that is, the phase of the SIG RF field is related to both the amplitude and phase of the beat signal. When the AM frequency of the LO RF field is the same as the frequency of the beat signal, the beat signal will further interfere with the AM of the LO RF field inside the atom, and then the amplitude of the beat signal is related to the phase of the SIG RF field. The amplitude of the beat signal and the phase of the SIG RF field show a linear relationship within the range of 0 to π/2 when the phase of the AM is set with a difference π/4 from the phase of the LO RF field. The minimum phase resolution can be as small as 0.6° by optimizing the experimental conditions according to a simple theoretical model. This study will expand and contribute to the development of RF measurement devices based on Rydberg atoms.

Evgenii B. Aleksandrov, O. V. Konstantinov, V. I. Perel

Arthur Bramley

Christof Bernhard, Bänz Bessire, André Stefanov +1 more

We demonstrate spectral amplitude and phase modulation of time-energy entangled photon pairs by means of a spatial light modulator (SLM) [1]. Coincidences are detected by sum frequency generation in a nonlinear crystal which has been applied in several experiments as an ultrafast coincidence detection method to temporally resolve entangled photons on a timescale of fs [2,3]. By taking into account the properties of the detection crystal, we derive an expression for the up-converted frequency signal in the form of a second-order correlation function G(1)[3]. This detection scheme is in contrast to a perfect coincidence detection described by the fourth-order correlation function G(2). However, in former two photon shaping experiments [1,2] the detected signal was compared to simulations based on G(2). We investigate here under which conditions the G(2)ceases to provide an accurate description of the measurements.

Andreas Bengtsson

In this work, we have designed, fabricated, and characterized two coupled superconducting microwave resonators.\n\nUsing this system, we investigate a parametric frequency conversion process in the microwave regime. We modulate the resonance frequency at the difference frequency between two modes, i.e. by three-wave mixing. An incoming signal, resonant with one of the modes, is then converted to the other mode. We demonstrate this behavior in several different schemes, e.g. using one or two modulation tones. We report a conversion efficiency of 50%, meaning that 50% of the incoming wave amplitude gets converted to the other frequency.\n\nFinally, we discuss the possibilities to use such a system in a quantum computing architecture.

V. N. Lugovoǐ