Researchers have experimentally validated a new method for creating entanglement between ions while suppressing unwanted interactions with nearby qubits. The team, led by Vikram Kashyap of the Joint Center for Quantum Information and Computer Science, NIST/University of Maryland, engineered a coupling matrix to selectively exclude interactions between target ions and their neighbors during entangling operations. This approach requires no prior measurement of crosstalk, a common challenge in trapped-ion quantum computing, and has been successfully demonstrated in a 3-ion string. “By controlling the geometric phases generated in the motional modes of the ion string, we engineer a coupling matrix that selectively excludes coupling between target and neighbor ions from the entangling operation,” the researchers state. Simulations show the method scales to a 20-ion string, potentially simplifying the construction of larger, more complex quantum processors.
Coupling Matrix Engineering for Crosstalk Insensitive Entanglement
The team demonstrated a method for designing entangling operations inherently resistant to crosstalk by meticulously shaping the qubit-qubit coupling matrix. This technique functions without requiring prior measurement of existing crosstalk levels, a simplification over conventional methods that demand characterization and compensation. Simulations reveal the method’s scalability to a 20-ion string, suggesting a pathway toward more complex quantum processors, and the researchers have experimentally validated this coupling matrix engineering in a smaller, 3-ion system. This precise control over ion interactions represents a departure from typical crosstalk mitigation strategies, and the ability to operate regardless of initial crosstalk levels could substantially reduce the complexity of building larger, more reliable quantum devices. “This approach requires no knowledge of the amount of crosstalk present,” explains the team, eliminating a key obstacle to scaling up trapped-ion quantum computing.
This approach functions without prior measurement of the crosstalk level, offering a significant advantage over existing techniques. Experimental validation occurred using a 3-ion string, confirming the feasibility of this method for achieving crosstalk-insensitive entanglement.
