These authors contributed equally * Correspondence should be sent to E.W.: edowaks@umd.edu
When an atom strongly couples to a cavity, it can undergo coherent vacuum Rabi oscillations.Controlling these oscillatory dynamics quickly relative to the vacuum Rabi frequency enables remarkable capabilities such as Fock state generation and deterministic synthesis of quantum states of light, as demonstrated using microwave frequency devices 1,2 . At optical frequencies, however, dynamical control of single-atom vacuum Rabi oscillations remains challenging. Here, we demonstrate coherent transfer of optical frequency excitation between a single quantum dot and a cavity by controlling vacuum Rabi oscillations. We utilize a photonic molecule 3-7 to simultaneously attain strong coupling and a cavity-enhanced AC Stark shift. The Stark shift modulates the detuning between the two systems on picosecond timescales, faster than the vacuum Rabi frequency. We demonstrate the ability to add and remove excitation from the cavity, and perform coherent control of light-matter states. These results enable ultra-fast control of atom-cavity interactions in a nanophotonic device platform.Much of the prior work investigating atomic systems strongly coupled to optical cavities has operated in the static regime. In this regime the coupling between the two systems remains constant and 2 the signature of strong coupling is observed either in the frequency domain in the form of vacuum Rabi splitting [8][9][10][11] , or by direct time-domain observation of vacuum Rabi oscillations 12 . Recently, there has been significant experimental progress in optically controlling the dynamical response of atomic systems strongly coupled to cavities for applications such as optical switching [13][14][15][16] , reversible storage of photonic qubits 17,18 , and hybrid quantum information processing 19,20 . These works have all operated in the adiabatic regime where the duration of the optical control pulse was long compared to the vacuum Rabi frequency.When the interaction between the atom and cavity is modulated fast compared the vacuum Rabi frequency, the system undergoes diabatic rapid passage. In this regime it becomes possible to coherently transfer energy between an atomic excitation and a cavity photon by directly controlling vacuum Rabi oscillations. This coherent transfer has been effectively implemented at microwave frequencies and has enabled capabilities such as Fock state generation 1 and synthesis of arbitrary photonic wavefunctions 2 . At optical frequencies, however, diabatic control of vacuum Rabi oscillations between a single atomic system and a cavity remains difficult.In this letter we report a demonstration of controlled transfer of excitation between a semiconductor quantum dot and a strongly coupled optical cavity by directly controlling vacuum Rabi oscillations diabatically. We use a pulsed AC Stark shift to control the detuning between the quantum dot and cavity on picosecond timescales, enabling ultra-fast control of light-matter intera...