Fabrication of sealed UHV glass enclosures designed for ion trapping and quantum computing

The goal of this program is to demonstrate the fabrication of cubic-centimeter-scale permanently sealed and evacuated fused silica enclosures containing linear Paul traps for trapped-ion-related applications, such as quantum computing. The proposed miniature, highly optically-accessible enclosures will be attached to a small pumping system, or be equipped with an internal cryosorption pump capable of maintaining ultrahigh vacuum (UHV) over prolonged periods. Since the vacuum chamber itself is made from fused silica, the proposed sealed UHV enclosure will be highly flexible in terms of integrating high optical quality sections to allow access for beams and fluorescence collection, and it will be compatible with a broad range of ion trap chip designs, including 2D and 3D traps. Several leading research institutions have shown that arrays of trapped ions offer unique capabilities for quantum information processing and quantum sensing, particularly at the fidelity frontier. However, the number of ions that can be co-trapped in a given trap while still retaining this high performance is limited, and it has been expected for some time that multiple traps linked by photonic interconnects will be required to scale the system even at the level of thousands of qubits. The heart of many of these experiments, the ion trap itself, has been translated to microfabricated platforms. However, broad utilization of ion traps is presently limited by the complexity of equipment needed to manipulate the ions and maintain a favorable operating environment, such as the bulky vacuum enclosure itself and the light conditioning and delivery systems. Among other specific technologies necessary to facilitate the effective implementation of gate-based quantum computing methods on intermediate scale quantum processors, there is a need to develop a UHV-compatible bonding technology that provides for the fabrication of miniaturized, completely sealed, non-magnetic enclosures equipped with high optical access for UV, visible, and NIR light. The sealing technique must allow for the inclusion in the enclosure of the ion trap(s) of interest and ancillary elements, including an atomic source. During the course of Phase I, fused silica elements were successfully welded, using a femtosecond laser-based welding process, combined with a proprietary surface preparation procedure. Prototypes were fabricated and shown to have a measured leak rate of less than 1e- 12 atm*cc/s, making them compatible with the envisioned UHV-applications. Further representative samples passed a series of stringent UHV helium leak tests, including tests conducted after cycling the test pieces to 77 K and to 473 K. The objective of the Phase II is to demonstrate the fabrication of permanently sealed and evacuated fused silica enclosures containing a linear Paul trap and an ion source. Means to measure the pressure inside this cubic-centimeter sealed enclosure will also be demonstrated.