Reconfigurable quantum computer juggles 98 qubits

Jie Luo, Brian Marinelli, Kyung-Hoon Lee +2 more

Shantanu Debnath, Norbert M. Linke, Caroline Figgatt +3 more

Chad Fertig, Ronald Legere, W. Suptitz +1 more

The authors present a preliminary measurement of the cold collision shift for /sup 87/Rb where they found the shift to be more than a factor of 10 smaller than that of a laser-cooled Cs clock. They also discuss calculations for /sup 85/Rb and demonstrate a juggling fountain. Juggling fountain clocks can achieve higher stability without requiring large improvements in the local oscillator. In this first Cs juggling experiment, the effects of collisions between juggled balls of atoms are studied.

Chad Fertig, J.I. Rees, Kurt Gibble

We demonstrate a new atomic state detection scheme that directly measures the population difference of the two clock states using FM absorption spectroscopy. We also demonstrate a juggling Rb fountain clock that we will use to study collisions of juggled balls of atoms. Juggling can significantly improve the clocks short-term stability without requiring greater signal-to-noise or a larger cold collision frequency shift.

Brian Marinelli, Luo, Jie, Hengjiang Ren +6 more

Realizing the advantages of quantum computation requires access to the full Hilbert space of states of many quantum bits (qubits). Thus, large-scale quantum computation faces the challenge of efficiently generating entanglement between many qubits. In systems with a limited number of direct connections between qubits, entanglement between non-nearest neighbor qubits is generated by a series of nearest neighbor gates, which exponentially suppresses the resulting fidelity. Here we propose and demonstrate a novel, on-chip photon exchange network. This photonic network is embedded in a superconducting quantum processor (QPU) to implement an arbitrarily reconfigurable qubit connectivity graph. We show long-range qubit-qubit interactions between qubits with a maximum spatial separation of $9.2~\text{cm}$ along a meandered bus resonator and achieve photon exchange rates up to $g_{\text{qq}} = 2π\times 0.9~\text{MHz}$. These experimental demonstrations provide a foundation to realize highly connected, reconfigurable quantum photonic networks and opens a new path towards modular quantum computing.