Abstract: Methods for pump-probe spectroscopy are provided. In an embodiment, such a method comprises directing pump light having a frequency ?pump at a location in a sample to excite a transition between two quantum states of a target entity in the sample, directing probe light at the location to generate a coherent output signal having a frequency ?output and a wavevector koutput, and detecting the output signal as the probe light is scanned over a range of frequencies. In the method, either the transition excited by the pump light is a multiphoton transition corresponding to a frequency difference of n*?pump, wherein n?2; or the probe light is a set of m coherent light pulses, each coherent light pulse having a frequency ?m and a wavevector km, wherein m?2; or both. Systems for carrying out the methods are also provided.

Abstract: Methods for pump-probe spectroscopy are provided. In an embodiment, such a method comprises directing pump light having a frequency ?pump at a location in a sample to excite a transition between two quantum states of a target entity in the sample, directing probe light at the location to generate a coherent output signal having a frequency ?output and a wavevector koutput, and detecting the output signal as the probe light is scanned over a range of frequencies. In the method, either the transition excited by the pump light is a multiphoton transition corresponding to a frequency difference of n*?pump, wherein n?2; or the probe light is a set of m coherent light pulses, each coherent light pulse having a frequency ?m and a wavevector km, wherein m?2; or both. Systems for carrying out the methods are also provided.