  We report the single crystal study of the bulk magnetization and neutron
scattering measurements on a quantum S=1/2 spin ladders system
IPA-Cu(Cl0.95Br0.05)3with quenched disorder. In zero field, the disordered spin
liquid phase is preserved as in pure IPA-CuCl3. Due to the bond randomness, a
different Bose glass phase was directly observed in Hc<H<H', which separates
the spin liquid phase from the unconventional Bose-Einstein condensation phase.
The observed finite value of boson compressibility dM/dH and lack of
field-induced three-dimensional long range order are consistent with the
theoretical prediction.
