Unless corrected by additional positional information (GPS, landmarks, etc.) inertial navigation is completely reliant on dead reckoning. Any system that uses

Unless corrected by additional positional information (GPS, landmarks, etc.) inertial navigation is completely reliant on dead reckoning. Any system that uses this has cumulative error. I'm guessing (like you) that these "quantum compasses" provide a much lower error, just now sure how much. The cumulative error always exists because any sensor introduces error (I'm ignorant of anything "quantum" though). This means if you have several inputs (velocimeter, accelerometer, gyroscope, magnetometer, etc.), you are introducing multiple forms of error, each with it's own error band. Interestingly, there is an algorithm called a Kalman filter that takes in all these inputs and can spit out a best estimate for navigation, it's pretty amazing.