Because ternary computer has more superiority than other d-ary number systems, we focus on the investigation of ternary elementary quantum gates and the synthesis algorithm of ternary quantum logic circuits. Above all, Pauli operators and their matrices on qutrit are introduced. Then eight qutrit operators are selected as elementary operators and eight qutrit quantum logic gates are defined. Permutation groups are introduced to characterize the quantum gates and quantum logic circuits. Some important qutrit quantum logic gates are defined also, such as QNOT, QKCXi, EQKCXi, QSwap, QCNOT and EQCNOT. Based on these elementary gates, we prove two very important theorems: (1) all qutrit quantum reversible logic circuit can be generated by Xi gate and QKCXi gate; (2) all qutrit quantum reversible logic circuits can be generated by Xi gate and QCNOT gate. The two theorems indicate that any complicated qutrit quantum reversible circuit can be constructed by the simplest ternary quantum gate. This will greatly simplify the implementation difficulty of quantum circuit. Subsequently, we propose a synthesis algorithm for qutrit quantum reversible logic circuit, which is verified through simulation experiment by the computer program we have designed.
Owing to the exponential nature of the memory or run-time complexity,many existing methods can only synthesize 3-qubit logic circuits using quantum logic gate library,however,a few can optimally synthesize 3-qubit logic circuits for quantum NOT,CNOT,Controlled-V and Controlled-V+(NCV)gates,the key approach reduces the NCV quantum circuit synthesis problem to four-valued logic synthesis.This paper proposes using NCV gates to create a new quantum logic gate library,which is exactly the same as NCV gate library in the synthesis of all optimal 3-qubit circuits,thus it also reduces the four-valued logic synthesis to easily solved two-valued logic synthesis.We present a 3-qubit efficient synthesis algorithms based on perfect hash function,which can quickly construct all optimal 3-qubit circuits——the average speed that synthesizes circuits with minimum cost is nearly 127 times faster than that of the best result of Maslov 2007.
Efficient constructions for quantum logic are essential since quantum computation is experimentally challenging. This thesis develops quantum logic synthesis as a paradigm for reducing the resource overhead in fault-tolerant quantum computing. The model for error correction considered here is the surface code. After developing the theory behind general logic synthesis, the resource costs of magic-state distillation for the
T=exp(iπ(I−Z)/8) gate are quantitatively analyzed. The resource costs for a relatively new protocol distilling multi-qubit Fourier states are calculated for the first time. Four different constructions of the fault-tolerant Toffoli gate, including two which incorporate error detection, are analyzed and compared. The techniques of logic synthesis reduce the cost of fault-tolerant quantum computation by one to two orders of magnitude, depending on which benchmark is used. Using resource analysis for
T gates and Toffoli gates, several proposals for constructing arbitrary quantum gates are compared, including "Clifford+
T" sequences,
V-basis sequences, phase kickback, and programmable ancilla rotations. The application of arbitrary gates to quantum algorithms for simulating chemistry is discussed as well. Finally, the thesis examines the techniques which lead to efficient constructions of quantum logic, and these observations point to even broader applications of logic synthesis.