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Constant-Cost Implementations of Clifford Operations and Multiply-Controlled Gates Using Global Interactions.
Sergey Bravyi1, Dmitri Maslov1, Yunseong Nam2
1IBM Quantum, IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, USA.
This study demonstrates that quantum circuits using global entangling gates can implement essential quantum operations efficiently. These circuits offer a significant advantage for quantum algorithms by reducing the number of required entangling gates.
Area of Science:
- Quantum Computing
- Quantum Information Science
Background:
- Quantum circuits are fundamental to quantum computation.
- Efficient implementation of unitary operators is crucial for developing practical quantum algorithms.
Purpose of the Study:
- To investigate the efficiency of quantum circuits utilizing global entangling gates.
- To determine the cost of implementing common quantum operations using these circuits.
Main Methods:
- Considered quantum circuits with single-qubit operations and global entangling gates derived from Ising-type Hamiltonians.
- Analyzed the gate complexity for implementing various unitary operators.
Main Results:
- Achieved constant-cost implementations of Clifford operations (with/without ancillae).
- Developed a constant-cost implementation for multiply-controlled gates using linear ancillae.
- Showcased an O(log*n) cost implementation for n-controlled single-target gates with logarithmic ancillae.
Conclusions:
- Circuits with global entangling gates offer a significant asymptotic advantage in terms of gate cost.
- This approach enables highly efficient execution of key quantum operations, advancing quantum algorithm design.
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