Physicists Demonstrate Qubit-Qutrit Entanglement
By Lisa Zyga physorg.com

For the first time, physicists have entangled a qubit with a ÒqutritÓ Ð the 3D version of the 2D qubit. Qubit-qutrit entanglement could lead to advantages in quantum computing, such as increased security and more efficient quantum gates, as well as enable novel tests of quantum mechanics.

The research team, composed of physicists from the University of Queensland, the University of Bristol, and the University of Waterloo, has published its results in a recent issue of Physical Review Letters. The researchers made qutrits with biphotons (two correlated photons), resulting in Òbiphotonic qutrits.Ó Then, they entangled these qutrits with photonic qubits (made with one photon) using a combination of linear optic elements and measurements.


A qutrit, just as it sounds, is the quantum information analogue of the classical trit. Due to its quantum mechanical nature, a qutrit can exist in superpositions of its three basis states. This is similar to how a qubit can exist in superpositions of its two states. Because of the qutritÕs 3D nature, though, it can carry much more information than the qubit. (A string of n classical bits holds 1n states, a string of n qubits holds 2n states, and a string of n qutrits holds 3n states.)