Inquantum computing, a qudit (/ˈkjuː/dɪt/) or quantum dit is the generalized unit of quantum information described by a superposition ofd states, where the number of states is an integer equal to or greater than two.
A qudit, characterized by d=2 states is aqubit .[1]
Qudits with d states greater than 2 can provide a larger Hilbert space, providing more ways to store and process quantum information.[2][3]
Quantum decoherence is the natural process where quantum information is lost due to environmental interaction andquantum error correction is a technique that actively combats decoherence.
In a paper published September 2025, researchers demonstrate a new hybrid method that encodes information in both light and matter using acat state qudit with d>2 which allows for the detection of photon loss through the parity syndrome by entangling a light pulse with ancillary qubits. This method achieves parallel Bell-pair generation by leveraging the multi-level nature of the qudit.[4]
The first open source qudit stabilizer simulator named "Sdim" was announced November 2025 in a pre-print paper on arXiv.[5]
Aqudit logic gate (or simplyqudit gate) is a basic quantum circuit that acts on a qudit.
To achieve a universal qudit gate, (a gate that can be used to approximate any unitary transformation on a quantum computer to an arbitrary degree of accuracy) a set of gates must include a finite set of single qudit gates and at least one two qudit entangling gate that can create entanglement between qudits.
Quantum information is traditionally used inRamsey interferometry, a technique used for precise measurement across various areas of science and technology.
Qudits with d>2 have shown to increase precision and resolution of quantum measurements. Qutrits, for example, have shown to achieve a twofold increase in resolution compared to qubits without any reduction in measurement contrast.[6]
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