# Quantum Music

## Create music using quantum state number distributions

### Visualization

-When we have a source of light that is so weak that it only emits a few photons, we can count the number of individual photons that are emitted during a certain amount of time - one second, for example. The number of photons that reach the detector during one second is called the photon count.

Say we measure the number of photons we get from a laser each second for ten seconds. This process is represented in the animation below:

Each blue bar in the graph represents a different photon count, so when two photons are detected, for example, the bar on the right will grow.

Now imagine taking measurements in the same way, but for one hundred seconds. If we put the results into a graph, we might see something like the graph below:

This graph shows that out of all the one-second divisions of time, the photon count was 0 for 10 of them, 1 for 50 of them, and 2 for 40 of them. This can be used to show that for 10/100 seconds, we will count 0 photons, or in other words, there is a 10/100 (10%) chance that the photon count will be 0. Similarly, there is a 50/100 (50%) chance of a photon count of 1, and a 40/100 (40%) chance of a photon count of 2. In the graph above, we can think of the numbers on the left as probability, not just the number of each photon count.

We call this type of graph a "probability distribution." It tells us how likely we are to count a number of photons in a certain amount of time. A real-life probability distribution might look like these:

These are the Thermal and Coherent states. The word "state" refers to a quantum state, which is a mathematical object used to calculate a probability distribution. These two states come from different sources of light. Thermal state light normally comes from hot objects, like lightbulbs and stars, and coherent state light comes from lasers.

The Quantum Music app takes data measured from quantum states and uses it to play music. Each photon count has a musical note assigned to it. The program takes measurements, like in the first animation, and plays the note that corresponds to the measured photon count.

If you listen carefully, you can hear the difference between the music created from the thermal and coherent states. From the graph of the thermal state, we can see that there is a high probability of a 0 photon count, which is represented in the music by silence. At higher tempos, this randomly spaced silence sounds like syncopation. There is also a chance of measuring 10 photons, which will result in a very high note. We can see in the graph of coherent state light that the probability is centered around 2 and 3, with smaller probabilities of the other photon counts. This means that the music will be mostly those two notes, with a few others in between.