In September 2024, the concert hall in Linz had more than just an orchestra on stage. Next to the musicians, a setup was generating pairs of entangled photons: a laser with a wavelength of 405 nm passed through a nonlinear crystal and split into two photons at 810 nm, which flew off to two measurement stations, Alice and Bob. Each station randomly chose one of two measurement bases in under 100 ms, and coincidences were recorded with a timing resolution better than 350 ps. The full cycle took about 400 ms, and it was these outcomes, not a prewritten score, that controlled the music.

Entanglement is like two dancers who, even at opposite ends of the stage, always move in sync: a turn by one instantly determines the other's pose. In the performance BruQner, the measured Bell S value reached about 2.45, well above the classical limit of 2, demonstrating a violation of the CHSH inequality. In the middle section, which used classically correlated data, S dropped below 2, and this difference was deliberately made audible through the choice of musical motifs. A listener without a single formula could sense where the familiar world of local realism ends and quantum nonlocality begins.

Previously, quantum correlations were only sonified: experimental data were taken and turned into sound after the fact. Now the structure of entanglement itself became the compositional principle. A two-dimensional quantum random walk governed transitions between eight musical "rooms," and histograms of sound events became three-dimensional landscapes unique to each performance. This is a new genre: quantum aleatoric music, where the degree of Bell inequality violation serves as a musical parameter.

The outlook extends beyond a single stage. Integration with quantum networks for distributed performances is possible, with entangled photons shared between cities. Researchers could explore how listeners perceive the difference between quantum and classical correlations and use that experience for science communication. A quantum conductor directing an orchestra through entangled particles is no longer a metaphor: it has already stepped onto the stage.