Measuring spin on electrons prepared in various directions

In summary, Alice runs two batches of 100 electrons, one with UP spin in the x-axis and the other with UP spin in the y-axis, through a spin measuring device. She records the time intervals for each electron's spin to be measured. Despite the initial alignment of the electrons, the average time-frame for the device to measure the spin is the same and therefore it is not possible for Alice to determine which batch she was working with based on the time intervals alone. The spin measuring device used is a Stern-Gerlach device, which relies on a magnetic field and has a certain probability of emitting a photon within a given time-frame.
  • #1
Jeronimus
287
9
Let's say we have 200 electrons.

The first batch of 100 of those electrons are prepared in a way that 50% are UP in the x-axis while 50% are DOWN in the x direction. The order is unknown.

The second batch of 100 electrons are prepared in the same manner but in the y axis.

Bob picks one of the two batches randomly and sends it to a spin measuring device.


Alice runs the batch sent to her through the spin measuring device, and checks for the x spin of all 100 electrons.
Alice writes down the time interval it took for the device to figure out the spin for each of the electrons individually.

Then she does the same for the other batch.


Is it possible for Alice to figure out which of the two batches she was working with, simply by looking at the time intervals it took the machine to figure out the spin of each electron?

From what i read, a spin measuring device is basically a magnetic field you put the electron in, and which then has a certain probability to emit a photon or not to emit a photon within a given time-frame.
Does the average time-frame it takes depend on the initial alignment of the electron or is it the same no matter which direction the electron was prepared in?
 
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  • #2
Jeronimus said:
Is it possible for Alice to figure out which of the two batches she was working with, simply by looking at the time intervals it took the machine to figure out the spin of each electron?
no.
From what i read, a spin measuring device is basically a magnetic field you put the electron in, and which then has a certain probability to emit a photon or not to emit a photon within a given time-frame.
Does the average time-frame it takes depend on the initial alignment of the electron or is it the same no matter which direction the electron was prepared in?

Google for "Stern-Gerlach device", and to the limits of our ability to measure these things, the time to get a measurement out of the device is independent of the initial spin state of the incoming particles.
(It's also worth taking a few minutes to think about how you would define the end points of this interval)
 

1. How do you measure the spin on electrons?

The spin on electrons can be measured using a technique called spin-polarized scanning tunneling microscopy (SP-STM). This involves passing a small current through the electron and measuring the changes in the electron's spin.

2. Can spin be measured on electrons prepared in different directions?

Yes, spin can be measured on electrons prepared in various directions. SP-STM allows for the measurement of spin in any direction, as long as the electron has a well-defined spin state.

3. What factors can affect the accuracy of spin measurement on electrons?

There are several factors that can affect the accuracy of spin measurement on electrons. These include external magnetic fields, temperature, and the quality of the sample being measured.

4. How is the spin of an electron related to its magnetic moment?

The spin of an electron is directly related to its magnetic moment. In fact, the magnetic moment of an electron is proportional to its spin, with a proportionality constant known as the gyromagnetic ratio.

5. Can spin measurement on electrons have practical applications?

Yes, spin measurement on electrons has many practical applications, particularly in the field of spintronics. This includes the development of new and more efficient electronic devices, such as spin-based transistors and memory storage devices.

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