Shannon's sphere packing bound (SPB) provides a fundamental limit for the spectral efficiency at short block lengths. This work combines polar codes and probabilistic amplitude shaping (PAS). Constant composition distribution matching (CCDM) is used to match uniformly distributed input bits to a desired amplitude distribution. A type check exploits the constant composition properties of CCDM in successive cancellation list (SCL) decoding. For a block length of 64~amplitude shift keying (ASK) symbols and a spectral efficiency of 1.5~bits per ASK symbol, polar coded PAS with outer cyclic redundancy check (CRC) codes and SCL decoding with type check outperforms state-of-the-art LDPC codes with PAS and performs within 0.8 dB of Shannon's SPB.
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