Microwave pulse sequences are the basis of coherent manipulation of the electronic spin ground state in nitrogen vacancy (NV) centers. In this work we demonstrate stimulated Raman transitions (SRTs) and stimulated Raman adiabatic passage (STIRAP), two ways to drive the dipole-forbidden transition between two spin sublevels in the electronic triplet ground state of the NV center. This driving is achieved by a two-photon Raman microwave pulse which simultaneously drives two detuned transitions via a virtual level for SRTs or via two adiabatic and partially overlapping resonant microwave pulses for STIRAP. We lay the theoretical framework of SRT and STIRAP dynamics and verify experimentally the theoretical predictions of population inversion by observing the dipole-forbidden transition in the ground state of a single NV center. A comparison of the two schemes showed better robustness and success of the spin swap for STIRAP compared to SRT.
Microwave pulse sequences are the basis of coherent manipulation of the electronic spin ground state in nitrogen vacancy (NV) centers. In this work we demonstrate stimulated Raman transitions (SRTs) and stimulated Raman adiabatic passage (STIRAP), two ways to drive the dipole-forbidden transition between two spin sublevels in the electronic triplet ground state of the NV center. This driving is achieved by a two-photon Raman microwave pulse which simultaneously drives two detuned transitions via a virtual level for SRTs or via two adiabatic and partially overlapping resonant microwave pulses for STIRAP. We lay the theoretical framework of SRT and STIRAP dynamics and verify experimentally the theoretical predictions of population inversion by observing the dipole-forbidden transition in the ground state of a single NV center. A comparison of the two schemes showed better robustness and success of the spin swap for STIRAP compared to SRT.
Shortcuts to adiabaticity~(STA) enables fast and robust coherent control of quantum system, which has been well placed in quantum technologies. In particular, inverse engineering STA provides much more freedom for the optimization of shortcut, which alleviates the complexity for experimental realization. Here, we implement a STA technique, known as invariant-based inverse engineering, to speed up the adiabatic control of the electron triplet ground state of a single nitrogen-vacancy~(NV) center. The microwave pulses to drive inversely engineered STA are obtained with space curve quantum control, where the evolution of spin transition is mapped to a three-dimensional closed space curve and the design of shortcut is obtained by optimization over the space curve. We demonstrate the fast and high-fidelity drive of dipole-forbidden transition between two spin sublevels of the ground state. Moreover, we demonstrate the robustness of the spin transition by introducing the detuning of driving microwave field. The acceleration and robustness is further confirmed by the comparison with two traditional Raman control schemes. Our results suggest invariant-based inverse engineering is powerful for fast and robust manipulation of NV system, and thus benefits quantum sensing and quantum computation based on the NV platform.
Shortcuts to adiabaticity (STA) enables fast and robust coherent control of quantum system, which has been well placed in quantum technologies. In particular, inverse-engineering STA provides much more freedom for the optimization of shortcut, which alleviates the complexity for experimental realization. Here, we implement a STA technique, known as invariant-based inverse engineering, to speed up the adiabatic control of the electron triplet ground state of a single nitrogen-vacancy (N-V) center. The microwave pulses to drive inversely engineered STA are obtained with space-curve quantum control, where the evolution of spin transition is mapped to a three-dimensional closed space curve and the design of shortcut is obtained by optimization over the space curve. We demonstrate the fast and high-fidelity drive of dipole-forbidden transition between two spin sublevels of the ground state. Moreover, we demonstrate the robustness of the spin transition by introducing the detuning of driving microwave field. The acceleration and robustness is further confirmed by the comparison with two traditional Raman control schemes. Our results suggest invariant-based inverse engineering is powerful for fast and robust manipulation of N-V system, and thus benefits quantum sensing and quantum computation based on the N-V platform.
Reaching a given target quantum state with high fidelity and fast operation speed close to the quantum limit represents an important goal in quantum information science. Here we experimentally demonstrate superadiabatic quantum driving to achieve population transfer in a three-level solid-state spin system at ambient conditions. Starting from traditional stimulated Raman adiabatic passage (STIRAP), our approach implements superadiabatic corrections to the STIRAP Hamiltonian with several pulse shapes, including the paradigmatic Gaussian shapes and trigonometric pulse shapes that guarantee an operation speed equal to the quantum limit. It requires no intense microwave pulses or long transfer times and shows an enhanced robustness against pulse imperfections. Thereby, these results might provide a useful tool for quantum information processing and the coherent manipulation of quantum systems.
By choosing the right system and using the right techniques, it is possible to achieve reliable control of an individual quantum system in a solid. Certain atom-like solid-state systems are especially suited for this goal. The electron spin of the diamond nitrogen-vacancy (NV) impurity center is a leader among such systems and has featured in a great deal of recent experimental work in the context of various quantum technologies. By extending optical control for the NV center we increase the utility of this system, opening it up to fresh applications in quantum optics. \n \nDoing quantum control with a solid-state spin comes with its own challenges. In particular it can be difficult to simultaneously isolate single systems, both for control and from environment-induced decoherence, while also coupling multiple systems together in a controlled way. A goal of the work presented in this dissertation is to develop techniques for answering this problem in the NV center. \n \nOptical control, as opposed to the microwave control usually used for state manipulation in the NV center, would make it easier to address only one spin system at a time. We demonstrate such control using two methods, two-photon optically driven Rabi oscillations and stimulated Raman adiabatic passage. These both have the added advantage that by using Raman-resonant, dipole-detuned optical fields, they protect the spin state from the decoherence normally associated with the optical transitions. Furthermore, we see that this electron spin control is nuclear spin dependent, providing a mechanism for coupling these two spin systems. \n \nWe also investigate a decoherence reduction technique that involves coupling continuous microwave fields to the spin states. The resulting "dressed states" are shielded from spin-bath-induced magnetic field fluctuations. We confirm this using optical coherent population trapping measurements which we have also developed in the NV center. We show that these measurements are sensitive to nuclear spin states as well as to dressed states. \n \nThese results supply the missing piece, optical spin manipulation, to control schemes that are all-optical, and they demonstrate ways to significantly push back the decoherence limit. \n \nThis dissertation includes previously published and unpublished co-authored material.
We propose a potentially practical scheme for quantum state transfer between a Cooper-pair box circuit and an electron spin ensemble of diamond nitrogen-vacancy (NV) centers. Both subsystems are placed into a common circuit QED and can be modeled as effective three-level subsystems under the appropriate external biases. Due to significant suppression of the photon decay, the robust state transfer between the two subsystems can be accomplished by using the technique of stimulated Raman adiabatic passage by individual microwave pulses, where a superconducting coplanar resonator serves as the quantum data bus. Numerical simulations show that the present scheme could offer a viable route towards robust quantum state transfer in hybrid solid-state systems.
Efficient initialization and manipulation of quantum states is important for numerous applications and it usually requires the ability to perform high fidelity and robust swapping of the populations of quantum states. Stimulated Raman adiabatic passage (STIRAP) has been known to perform efficient and robust inversion of the ground states populations of a three-level system. However, its performance is sensitive to the initial state of the system. In this contribution we demonstrate that a slight modification of STIRAP, where we introduce a non-zero single-photon detuning, allows for efficient and robust population swapping for any initial state. The results of our work could be useful for efficient and robust state preparation, dynamical decoupling and design of quantum gates in ground state qubits via two-photon interactions.