Microwave near-fields on atom chips

摘要

Microwave near-fields are a key ingredient for quantum information processing with atom chips. Our goal is to realize a quantum gate with the following features: The qubit is encoded in the hyperfine states |1> ≡ |F=1, m{sub}F=-1> and |2> ≡ |F=2, m{sub}F=+1> of 87{sup left}Rb, which are both magnetically trappable and allow for very long coherence lifetimes [1]. Microwave near-fields guided on the atom chip are used to drive single-qubit rotations and provide state-selectivity to the magnetic trapping potential. The quantum phase gate is implemented by state-selective collisions of two qubit atoms in this potential [2]. Besides applications in quantum information processing, microwave near-fields on atom chips can also be used for atom interferometry and chip-based atomic clocks. In our experiment, we have integrated miniaturized microwave guiding structures on an atom chip, using a newly developed lithographic fabrication process for chips with multiple layers of metallization (Fig. 1(a)). The structures are used to generate microwave near-fields with strong gradients on a micrometer scale. Through microwave dressing of atomic hyperfine states, state-selective double-well potentials for 87{sup left}Rb atoms can be created on our atom chip. Such potentials are the basic building block for the collisional quantum phase gate (Fig. 1(b) and [2]). We present the status of our experiment on state-selective coherent manipulation of atoms in the microwave potentials on our chip.