We construct an exact $n$-bit quantum adder with $O(n)$ gates and $O(\log n)$ depth that requires no ancillary qubits. The circuit uses only $X$, CNOT, and Toffoli gates under all-to-all connectivity and is classically reversible. Our construction accelerates the controlled ladder underlying addition. Grouping the data...
Jun-Hong Nie, Jia-Liang Tang, Xiao-Ming Sun et al.· 0 citations
Protecting quantum information from noise is essential for reliable quantum computation and quantum memories. Quantum state purification addresses this challenge by processing multiple noisy copies of an unknown quantum state to produce an output state of higher fidelity. Here we establish nearly tight upper and lower...
Jia-Liang Tang, Jun-Hong Nie, Ke-Ming He et al.· 0 citations
This work studies the depth-ancilla tradeoffs of Hamming weight computation under two qubit connectivity models, all-to-all and two-dimensional nearest-neighbor square grid (2D), in both the standard and dynamic circuit models.
Wei Zi, Pei Yuan, Jun-Hong Nie et al.· 0 citations
We study the trace distance \[D_{\mathrm{tr}}(\rho,\sigma) =\frac12\|\rho-\sigma\|_1, \rho=\bigotimes_{i=1}^n\rho_i,\quad \sigma=\bigotimes_{i=1}^n\sigma_i, \] when the two exponentially large states are specified by their local factors. We give a deterministic approximation within a universal constant factor for ratio...
Kun He, Dimitrios Myrisiotis, Jun-Hong Nie et al.· 0 citations
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