Quantum Mechanics: Measurement.

(Quantum measurement) Alice and Bob each performs a series of experiments to test a certain state-preparation device for spin-1/2 particles. Alice performs a series of measurements on Oz, her test result is that the device is producing a mixed state with 50% particles having the state vector | Oz =+1) and 50% having the state vector | Oz --1). Similarly, Bob performs a series of measurements on Oy and concludes that the device is producing a mixed state with 50% particles having the state vector | Ox =+1) and 50% having the state vector | Ox=-1). Is there any measurement that you can perform to resolve their argument?" If yes, describe it, otherwise, show that such a measurement does not exist. (Quantum measurement) Alice and Bob each performs a series of experiments to test a certain state-preparation device for spin-1/2 particles. Alice performs a series of measurements on Oz, her test result is that the device is producing a mixed state with 50% particles having the state vector | Oz =+1) and 50% having the state vector | Oz --1). Similarly, Bob performs a series of measurements on Oy and concludes that the device is producing a mixed state with 50% particles having the state vector | Ox =+1) and 50% having the state vector | Ox=-1). Is there any measurement that you can perform to resolve their argument?" If yes, describe it, otherwise, show that such a measurement does not exist